In the 24th Chapter of Luke Christ Jesus after being resurrected from the dead assures His Apostles that He is not a sprit but is flesh and bone and proves it by eating broiled fish with them.
Christ who had previously explained while in mortality that He was The “I AM” or “Jehovah” of the Old Testament was handled by many people after His resurrection. He had people put their fingers in the nail prints of His hands and feet and feel the scar of the sword in His side.
There are three entities of “The Godhead”, The Father, The Son and The Holy Ghost. In Luke 24 Christ reminds The Apostles that He would do as His Father had promised (sending the Holy Ghost) Christ told us He would send The Comforter, or The Holy Ghost to us after He left.
Prior to the first universal Christian council of The Church which the Emperor Constantine convened in 325AD the Trinity that we preach now was nowhere near universal but originated in Greece and migrated west slowly. Constantine liked the Doctrine the eastern church had of the Trinity, it was a perfect way to meld the beliefs of multiple gods with the doctrine of one god. Constantine was the defacto leader of a different religion by virtue of being Emperor so he had to walk a fine line concerning religion. I don’t envy Constantine for trying to keep a large nation together while in religious flux. He had his hands full.
Constantine in that council made the confession of the Trinity doctrine something that all Christians must confess and made the bishops in attendance of the council agree to it. Many bishops would not adhere and left the council under severe threats of punishment. Later Constantine relented and did not “force” bishops to teach the doctrine of the Trinity but later in 385 another council was convened where the doctrine be came mandatory under threat of death or banishment. There were minor differences in the Trinity doctrine of the eastern churches and the Roman churches for a few hundred years but now most if not all of the churches who call themselves catholic, including protestant churches have the same profession of faith including the same doctrine of The Holy Trinity.
First century believers would find the current popular Christian teaching on “The Holy Trinity” very confusing and would likely be repulsed by it.
There are many confusing verses in The Bible that make the current teaching of The Holy Trinity plausible or possible but there are also others that completely discredit that doctrine.
There are 3 distinct entities in The Godhead. We know for certain that at least one of the entities, Christ, has a physical body.
I believe that in order to communicate with God our spirit communicates with The Holy Ghost who is a being of spirit who communicates with God and we do that in the name of Jesus Christ.
I know my views are not considered kosher by the vast majority of Christians, certainly my views don’t adhere to what the Catholic Church (being the universal church not a particular church) describes when defining God. I read The Holy Bible for the first time cover to cover when I was 15 years old and have read it many times since. When I speak to priests and ministers of different churches (being a singer I used to sing in many churches) they tell me that I can’t possibly understand The Holy Bible because I haven’t been to Seminary. Perhaps, but the early Apostles didn’t go to seminary either.
Does any of this make a difference. I don’t know how important it is to know the mechanics of the being of God. I know it is important that Christ took upon Himself a physical body and came to earth to suffer for my sin and be punished to death to atone for my sins. I know that if I confess that and confess that Jesus Christ is The Son of God and is My and the worlds Savior then I can qualify for His Grace and spend eternity with Him. I know that we prove that we follow Him by our actions in this life of mortality.
Not sure what it is your stating you think is controversial.
It is from the "first century believers" that we have the divinely inspired New Testament Scriptures they wrote which teach the Triunity of God both as Jesus taught as well as that revealed by the Holy Spirit. Where else would the later theologians gather the proofs in order to describe/define it? Many, many places in the Old Testament also teach it. Though it may have taken a few centuries for the religious leaders to get around to defining the doctrine in precise theological terms, it was taught and accepted by the Apostles, their disciples and passed down to other Christians. That's not to say there weren't controversies and disagreements but there is more than enough in Scripture that God has provided us to prove the truth of the doctrine.
I’m not so sure that God expects us to *understand* the concept of His nature.
The finite cannot fathom the infinite, nor the mortal, immortality, nor the temporal, the eternal.
Perhaps some day we will understand it better, but seems to me nobody had to pass a theology test to be saved. The pharisee and publican come to mind. God, be merciful to me a sinner.