Behold, my servant shall deal prudently, he shall be exalted and extolled, and be very high. As many were astonied at thee; his visage was so marred more than any man, and his form more than the sons of men: So shall he sprinkle many nations; the kings shall shut their mouths at him: for that which had not been told them shall they see; and that which they had not heard shall they consider. Who hath believed our report? and to whom is the arm of the LORD revealed? For he shall grow up before him as a tender plant, and as a root out of a dry ground: he hath no form nor comeliness; and when we shall see him, there is no beauty that we should desire him. He is despised and rejected of men; a man of sorrows, and acquainted with grief: and we hid as it were our faces from him; he was despised, and we esteemed him not. Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted. But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed. All we like sheep have gone astray; we have turned every one to his own way; and the LORD hath laid on him the iniquity of us all. He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth. He was taken from prison and from judgment: and who shall declare his generation? for he was cut off out of the land of the living: for the transgression of my people was he stricken. And he made his grave with the wicked, and with the rich in his death; because he had done no violence, neither was any deceit in his mouth. Yet it pleased the LORD to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand. He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities. Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he hath poured out his soul unto death: and he was numbered with the transgressors; and he bare the sin of many, and made intercession for the transgressors.
And unto the angel of the church in Thyatira write; These things saith the Son of God, who hath his eyes like unto a flame of fire, and his feet are like fine brass; I know thy works, and charity, and service, and faith, and thy patience, and thy works; and the last to be more than the first. Notwithstanding I have a few things against thee, because thou sufferest that woman Jezebel, which calleth herself a prophetess, to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols. And I gave her space to repent of her fornication; and she repented not. Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds. And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works. But unto you I say, and unto the rest in Thyatira, as many as have not this doctrine, and which have not known the depths of Satan, as they speak; I will put upon you none other burden. But that which ye have already hold fast till I come. And he that overcometh, and keepeth my works unto the end, to him will I give power over the nations: And he shall rule them with a rod of iron; as the vessels of a potter shall they be broken to shivers: even as I received of my Father. And I will give him the morning star. He that hath an ear, let him hear what the Spirit saith unto the churches.
For God so loved the world that He gave His only begotten Son, that whomsoever believeth in Him shall not perish but have everlasting Life. John 3:16
And again, when the 'leadership' of Judaism in His day asked Jesus what work God required for salvation, Jesus answered simply:
Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent. John 6:29
When Jesus asked the disciples whom the people said He is and then 'but whom say you that I AM', Peter's Holy Spirit inspired response is so true, so complete, so absolutely based upon God's Promise that Jesus expounded on the process to come (you know, the keys and the foundation rock):
And Simon Peter answered and said, Thou art the Christ, the Son of the living God. Matthew 16:16
And in his letters Paul echoed this same simple formula and not anything else:
That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. Roman 10:9
And Peter echoed this same simple Gospel when he preached in the home of Cornelius:
How God anointed Jesus of Nazareth with the Holy Ghost and with power: who went about doing good, and healing all that were oppressed of the devil; for God was with him. And we are witnesses of all things which he did both in the land of the Jews, and in Jerusalem; whom they slew and hanged on a tree: Him God raised up the third day, and shewed him openly ... And he commanded us to preach unto the people, and to testify that it is he which was ordained of God to be the Judge of quick and dead. To him give all the prophets witness, that through his name whosoever believeth in him shall receive remission of sins. Acts 10:38 - 44
And we see how God affirmed this Gospel immediately, even before Peter finished his sermon!
While Peter yet spake these words, the Holy Ghost fell on all them which heard the word.
And that, dear Catholic is the Gospel of Salvation, complete, not needing anything else to be real and immediate. Believe that Jesus is the one God has sent for our Salvation, believe God has raised Him from the dead as your Savior, and you are then IN eternal life, by the Promise of God, not some man-made institution. Your eternal life with God begins with that utterance/confession of faith, because it is at that moment that God's Holy Spirit enters to indwell you and as far as you let, he changes you into what He finds 'comely'. For it is God Who is in you, both to will and do of His good pleasure, from the moment of your profession onward.