I'm sorry for having to ping you to this thread, but I thought it only fair to let you know that you were being accused of something without you knowing about it. I am more than happy to explain my beliefs. As to the Scriptures affirming the existance of the Triune God-head, the Trinity, one of the better sites that does a good job of this is http://www.layevangelism.com/qreference/chapter10.htm. They start out by saying:
The Trinity
Isaiah 48:16 "Come near to Me, listen to this: from the first I have not spoken in secret, from the time it took place, I was there, and now Adonai-Yehovah has sent Me and His Spirit." [Indication of the Son and the Holy Spirit being a person & the Trinity] (John 18:20, Jesus said this referred to Him; John 13:19, 14:29)
Matthew 3:16-17 "And after being baptized, Jesus went up immediately from the water; and behold, the heavens were opened, and he saw the Spirit of God descending as a dove, and coming upon Him, and behold, a voice out of the heavens, saying, ‘This is My beloved Son, in whom I am well-pleased.’" (Luke 3:21-22)
Matthew 28:18-20 "And Jesus came up and spoke to them, saying, ‘All authority has been given to Me in heaven and on earth. go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit, teaching them to observe all that I commanded you, and lo, I am with you always, even to the end of the age.’"
Ephesians 5:18-20 "And do not get drunk with wine, for that is dissipation, but be filled with the Spirit, speaking to one another in psalms and hymns and spiritual songs, singing and making melody with your heart to the Lord; always giving thanks for all things in the name of our Lord Jesus Christ to God, even the Father."
1 Peter 1:2 "According to the foreknowledge of God the Father, by the sanctifying work of the Spirit, that you may obey Jesus Christ and be sprinkled with His blood: May grace and peace be yours in fullest measure."
1 John 5:7 "For there are three that bear record in heaven, the Father, the Word, and the Holy Spirit; and these three are one."
Jude 20-21 "But you, beloved, building yourselves up on your most holy faith; praying in the Holy Spirit; keep yourselves in the love of God, waiting anxiously for the mercy of our Lord Jesus Christ to eternal life."
Hebrews 1:8 "But of the Son He says, ‘Your throne, O God [Elohim, !yhiloa>], is forever and ever, and the righteous scepter is the scepter of Your kingdom.’"
Psalm 45:6 "Your throne, O Elohim, is forever and ever, a scepter of uprightness is the scepter of your kingdom." (Jesus is Elohim)
2 Timothy 1:2 "Grace, mercy and peace from God the Father and Christ Jesus our Lord." (The Father is God)
Philippians 2:10-11 "that at the name of Jesus every knee should bow, of those who are in heaven, and on earth, and under the earth, and that every tongue should confess that Jesus Christ is aAdonai, to the glory of God the Father." (From Isaiah 45:21-23. Jesus is Yehovah)
Isaiah 45:21-23 "Declare and set forth your case; indeed, let them consult together. Who has announced this from of old? Who has long since declared it? Is it not I, Yehovah? And there is no other Elohim besides Me, a righteous El and a Savior; there is none except Me. Turn to Me, and be saved, all the ends of the earth; for I am El, and there is no other. I have sworn by Myself, the word has gone forth from My mouth in righteousness and will not turn back, that to Me every knee will bow, every tongue will swear allegiance." (Phil 2:10-11, Jesus is Yehovah)
John 1:1 "In the beginning was the Word, and the Word was with God and the Word was God [qeo;" h\\n oJ logo"]. And the Word became flesh, and dwelt among us." (Jesus is God)
John 1:18 "No man has seen God at any time; the only begotten God, who is in the bosom of the Father, He has explained Him." (This means that the appearances of Yehovah God in the O.T. are not the Father, but Jesus-Yehovah, Genesis 18:1, because no one has ever seen the Father)
Genesis 18:1 "Now Yehovah appeared to him by the oaks of Mamre, while he was sitting at the tent door in the heat of the day." (Jesus appeared to him, John 1:18)
Acts 5:3-4 "But Peter said, ‘Ananias, why has Satan filled your heart to lie to the Holy Spirit, and to keep back some of the price of the land? While it remained unsold, did it not remain your own? And after it was sold, was it not under your control? Why is it that you have conceived this deed in your heart? You have not lied to men, but to God.’" (The Holy Spirit is God)
Isaiah 40:13-18 "Who has directed [Spirit-Yehovah, hw:hy]Aj'Wr] Ruach- Yehovah, Or as His counselor has informed Him? With whom did He consult and who gave Him understanding? And who taught Him in the path of justice and taught Him knowledge, and informed Him of the way of understanding?. . . . To whom then will you liken El? Or what likeness will you compare with Him?" (The Holy Spirit is Yehovah)
Isaiah 64:8 "But now, Yehovah, You are our-Father, we are the clay, and You our potter; and all of us are the work of Your-hand." (The Father is Yehovah)
John 1:1-3 "In the beginning was the Word, and the Word was with God and the Word was God. This One was in the beginning with God. All things came into being by Him, and apart from Him nothing came into being that has come into being." (Jesus is God in the flesh)
Colossians 1:15-18 "And He is the image of the invisible God, the firstborn of all creation. For by Him all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities— all things have been created by Him and for Him. And He is before all things, and in Him all things hold together. He is also head of the body, the church; and He is the beginning, the first-born from the dead; so that He Himself might come to have first place in everything." (Jesus is Yehovah-Creator)
Hebrews 1:3 "And He is the reflected-brightness of His glory and the exact-image of His essence, and upholds all things by the word of His power. When He had made purification of sins, He sat down at the right hand of the Majesty on high." (Jesus is God)
Job 33:4 "Ruach-Elohim has made me, And the breath of the Almighty gives me life." (The Holy Spirit is Elohim)
Job 26:13 ""By His Spirit [j’Wr] the heavens are made-brightly-beautiful [hr;p]vi]; His hand has pierced the fleeing serpent." (The Holy Spirit is Creator-Yehovah)
1 Thessalonians 1:10 "and to wait for His Son from heaven, whom He raised from the dead, that is Jesus, who delivers us from the wrath to come." (The Father raises from the dead)
John 6:44 "No one can come to Me, unless the Father who sent me draws him; and I will raise him up on the last day." (Jesus raises from the dead)
John 11:25-26 "I am the Resurrection and the Life; he who believes in Me shall live even if he dies, and everyone who lives and believes in Me shall never die." (Jesus raises from the dead)
Romans 8:11 "But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who indwells you." (The Holy Spirit raises from the dead)
1 Kings 8:27 "But will Elohim indeed dwell on the earth? Behold, heaven and the highest heaven cannot contain You, how much less this house which I have built!" (The Father is everywhere)
Matthew 28:20 "Lo, I am with you always, even to the end of the age." (Jesus is everywhere)
Psalm 139:7 "Where can I go from Your Spirit? Or where can I flee from Your presence?" (The Holy Spirit is everywhere)
2 Corinthians 6:16 "Or what agreement has the temple of God with idols? For we are the temple of the living God; just as God said, "I will dwell in them and walk among them; and I will be their God, and they shall be My people." (The Father dwells in us)
Ephesians 4:6 "One God and Father of all who is over all and through all and in all."
1 John 2:23 "Whoever denies the Son does not have the Father; the one who confesses the Son has the Father also."
2 John 1:9 "Anyone who goes too far and does not abide in the teaching of Christ, does not have God; the one who abides in the teaching, he has both the Father and the Son." (Jesus dwells in us)
Revelation 3:20 "Behold, I stand at the door and knock; if any one hears My voice and opens the door, I will come into him, and will dine with him, and he with Me."
Colossians 1:27 "To whom God willed to make known what is the riches of the glory of this mystery among the Gentiles, which is Christ in you, the hope of glory."
2 Corinthians 13:5 "Test yourselves to see if you are in the faith; examine yourselves! Or do you not recognize this about yourselves, that Jesus Christ is in you—unless indeed you fail the test?"
John 14:17 "That is the Spirit of Truth, whom the world cannot receive, because it does not behold Him or know Him, but you know Him because He abides with you, and will be in you." (The Holy Spirit indwells us)
1 Corinthians 6:19 "Or do you not know that your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own?"
1 John 3:20 "God is greater than our heart, and knows all things." (The Father knows all things)
John 16:30 "Now we know that You know all things." (Jesus knows all things)
1 Corinthians 2:10-11 "For to us God revealed them through the Spirit; for the Spirit searches all things, even the depths of God. For who among men knows the thoughts of a man except the spirit of the man, which is in him? Even so the thoughts of God no one knows except the Spirit of God." (The Holy Spirit knows all things)
1 Thessalonians 5:23 "Now may the God of peace Himself sanctify you entirely." (The Father Sanctifies us)
1 Corinthians 1:30 "But by His doing you are in Christ Jesus, who became to us wisdom from God, righteousness and sanctification, and redemption" (Jesus Sanctifies us)
Hebrews 2:11 "For both He who sanctifies and those who are sanctified are all from one Father; for which reason He is not ashamed to call them brethren."
Hebrews 10:10 "By this will we have been sanctified through the offering of the body of Jesus Christ once for all."
1 Peter 1:2 "According to the foreknowledge of God the Father, by the sanctifying work of the Spirit, that you may obey Jesus Christ and be sprinkled with His blood" (The Holy Spirit Sanctifies us)
Genesis 2:7 "Then Yehovah Elohim formed man of dust from the-ground, and breathed into his-nostrils the breath of lives; and man became-a-living soul." (The Father gives life)
John 1:3 "All things came into being by Him, and apart from Him nothing came into being that has come into being." (Jesus gives life)
John 5:21 "For just as the Father raises the dead and gives them life, even so the Son also gives life to whom He wishes."
John 6:63 "It is the Spirit who creates-life, the flesh profits nothing."
2 Corinthians 3:5-6 "Not that we are adequate in ourselves to consider anything as coming from ourselves, but our adequacy is from God, who also made us adequate as servants of a new covenant, not of the letter, but of the Spirit; for the letter kills, but the Spirit creates-life." (The Holy Spirit gives life)
1 John 1:3 "What we have seen and heard we proclaim to you also, that you also may have fellowship with us; and indeed our fellowship is with the Father, and with His Son Jesus Christ." (We have fellowship with the Father & the Son)
1 Corinthians 1:9 "God is faithful, through whom you were called into fellowship with His Son, Jesus Christ our Lord." (We have Fellowship with Jesus)
2 Corinthians 13:14 "The grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit, be with you all." (We have Fellowship with the Holy Spirit)
Psalm 90:2 "Before the mountains were born, or You did give birth to the earth and the world, even from everlasting to everlasting, You are El." (The Father is from eternity)
Micah 5:2 "But as for you, Bethlehem Ephrathah, too little to be among the clans of Judah, from you One will go forth for Me to be ruler in Israel. His goings forth are from long ago, from the days of eternity." (Jesus is from eternity)
John 8:58 "Jesus said to them, ‘Truly, truly, I say to you, before Abraham was born I AM.’"
Hebrews 9:14 "How much more will the blood of Christ, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?" (The Holy Spirit is from eternity)
Luke 22:42 "Father, if You are willing, remove this cup from Me; yet not My will, but Your’s be done." (The Father & the Son have a will)
1 Corinthians 12:11 "But one and the same Spirit works all these things, distributing to each one individually just as He wills." (The Holy Spirit has a will)
Matthew 3:17 "And behold, a voice out of the heavens, saying, ‘This is My beloved Son, in whom I am well-pleased.’" (The Father speaks)
Luke 5:20 "And seeing their faith, He said, ‘Friend, your sins are forgiven you.’" (Jesus speaks)
Luke 7:48 "And He said to her, ‘Your sins have been forgiven.’"
Acts 8:29 "And the Spirit said to Philip, ‘Go up and join this chariot.’" (The Holy Spirit speaks)
Acts 11:12 "And the Spirit told me to go with them without misgivings."
Acts 13:2 "And while they were ministering to the Lord and fasting, the Holy Spirit said, ‘Set apart for Me Barnabas and Saul for the work to which I have called them.’"
John 3:16 "For God so loved the world, that He gave His only begotten Son, that whoever believes in Him should not perish, but have eternal life." (The Father loves us)
Ephesians 5:25 "Husbands, love your wives, just as Christ also loved the church and gave Himself up for her." (Jesus loves us)
Romans 15:30 "Now I urge You, brethren, by our Lord Jesus Christ and by the love of the Spirit, to strive together with me in your prayers to God for me." (The Holy Spirit loves us)
Jeremiah 17:10 "I, Yehovah, search the heart, I test the mind, even to give to each man according to his ways, according to the results of his deeds." (The Father searches our hearts)
Revelation 2:23 "I am He who searches the reins and hearts; and I will give to each one of you according to your deeds." (Jesus searches the heart, thus claiming Jer 17:10 for Himself)
1 Corinthians 2:10 "For to us God revealed them through the Spirit; for the Spirit searches all things, even the depths of God." (The Holy Spirit searches our hearts)
Psalm 24:1 "The earth is Yehovah's, and all it contains; the world, and those who dwell in it." (We belong to the Father)
John 17:6 "I manifested Your name to the men whom You gave to Me out of the world. Your’s they were, and You gave them to Me, and they have kept Your word." (We belong to Jesus)
1 Corinthians 6:19-20 "Or do you not know that your body(We belong to the Holy Spirit)
Isaiah 43:10-11 "‘You are My witnesses,’ declares Yehovah, ‘And My servant whom I have chosen, in order that you may know and believe Me, and understand that I am He. Before Me there was no El formed, and there will be none after Me. I, even I, am Yehovah; and there is no Savior besides Me.’" (The Father Claims to be Savior alone)
1 Timothy 1:1 "Paul, an apostle of Christ Jesus according to the commandment of God our Savior, and of Christ Jesus, who is our hope."
1 Timothy 2:3 "This is good and acceptable in the sight of God our Savior."
1 Timothy 4:10 "We have fixed our hope on the living God, who is the Savior of all men, especially of believers."
Matthew 1:21 "And she will bear a Son; and you shall call His name Jesus, for it is He who will save His people from their sins. Now all this took place that what was spoken by the Lord through the prophet might be fulfilled, saying, ‘Behold, the virgin shall be with child, and shall bear a son, and they shall call his name Immanuel,’ which translated means, ‘God with us.’" (Jesus is God in the flesh who saved us from our sins)
John 3:17 "For God did not send the Son into the world to judge the world, but that the world should be saved through Him. (Luke 9:56)
Luke 9:56 "For the Son of Man did not come to destroy men’s lives, but to save them."
Titus 1:4 "Grace and peace from God the Father and Christ Jesus our Savior."
Titus 3:5-6 "He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit, whom He poured out upon us richly through Jesus Christ our Savior."
Romans 8:9 "But if anyone does not have the Spirit of Christ, he does not belong to Him."
1 John 4:13 "By this we know that we abide in Him and He in us, because He has given us of His Spirit."
Ephesians 1:13-14 "In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of promise, who is given as a pledge of our inheritance, with a view to the redemption of God's own possession, to the praise of His glory." (The Holy Spirit is Given as assurance of our salvation in Jesus)
Matthew 4:10 "Then Jesus said to him, "Begone, Satan! For it is written, ‘You shall worship the Lord Your God, and serve Him only.’" (Deut 6:13, 10:20, we serve the Father)"
Colossians 3:24 "It is the Lord Christ whom you serve." (We are serving Jesus)
John 6:63 "It is the Spirit who creates-life, the flesh profits nothing."
Romans 8:14 "For all who are being led by the Spirit of God, these are sons of God." (we are led by and serve the Holy Spirit)
John 14:1 "Let not your heart be troubled: ye believe in God, believe also in me. (We are to believe in the Father & Jesus)
Matthew 12:31-32 "Therefore I say to you, any sin and blasphemy shall be forgiven men, but blasphemy against the Spirit shall not be forgiven. And whoever shall speak a word against the Son of Man, it shall be forgiven him; but whoever shall speak against the Holy Spirit, it shall not be forgiven him, either in this age, or in the age to come." (We are to believe in and obey the Holy Spirit)
Hebrews 3:7-8 "Therefore, just as the Holy Spirit says, "Today if you hear His voice, do not harden your hearts as when they provoked Me, as in the day of trial in the wilderness."
Psalm 16:11 "You will make known to me the path of life; in Your presence is fulness of joy; In Your right hand there are pleasures forever." (The Father gives joy)
John 15:11 "These things I have spoken to you, that My joy may be in you, and that your joy may be made full." (Jesus gives us joy)
Romans 14:7 "For the kingdom of God is not eating and drinking, but righteousness and peace and joy in the Holy Spirit." (The Holy Spirit gives us joy)
John 12:48-50 "He who rejects me, and does not receive My sayings, has one who judges him; the word I spoke is what will judge him at the last day. For I did not speak on My own initiative, but the Father Himself who sent Me has given Me commandment, what to say, and what to speak. And I know that His commandment is eternal life; therefore the things I speak, I speak just as the Father has told Me."
John 5:22-23 "For not even the Father judges anyone, but He has given all judgment to the Son, in order that all may honor the Son, even as they honor the Father, he who does not honor the Son does not honor the Father who sent Him."
John 16:7-11 "But I tell you the truth, it is to your advantage that I go away; for if I do not go away, the Helper shall not come to you; but if I go, I will send Him to you. And He, when He comes, will convict the world concerning sin, and righteousness, and judgment; concerning sin, because they do not believe in Me; and concerning righteousness, because I go to the Father, and you no longer behold Me; and concerning judgment, because the ruler of this world has been judged."
The list above is not exhaustive. This link also discusses the common arguments against the Trinity, so I sincerely hope you will take a look at it as well as anyone else who wants to know why Christians believe in the Trinity. The early Christians DID believe in this truth, though it wasn't until the Council of Nicea that the doctrine was spelled out in a succinct way in a "creed". This was a human attempt to describe something that I don't think is humanly possible to fully understand but we DO have quite a lot of Scripture that proves it to be something God desires we know about Him. Even though we may not understand it all, it is another doctrine that is accepted by faith just like knowing we are saved by faith in Christ - and that we have eternal life through Him. We can know the truths about our faith because God has preserved those truths in Holy Scripture - and God does NOT change.