That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the word of life (I John 1:1).
It has been said, quite cogently, that Johns gospel assumes the humanity and undertakes to prove the deity of Jesus Christ, whereas Johns first Epistle assumes His deity, and then seeks to prove His humanity. The Lord Jesus Christ was both fully God and perfect Man.
John, in his gospel, says: These are written that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through His name (John 20:31). In his Epistle, he says: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God (I John 4:2,3).
His deity had been fully demonstrated by His mighty miracles, by His bodily resurrection. However, there were many who questioned His true humanity in Johns day, as they do in ours. Even today, many cultists, as well as liberals, try to make a distinction between the man, Jesus of Nazareth (whose absolute deity they reject), and the Christ, an ideal spirit, or idea of some sort, who is not actually a living being, but who may come upon or indwell certain people at times.
Such a concept John vehemently rejects, attributing it to the spirit of Antichrist. They had heard Him; they had seen Him; they had intensely examined Him; they had touched and handled Him. There was no doubt whatever that, both before and after His resurrection, He was a true manin fact, a perfect manman as God intended man to be. He could die for our sins, because He was sinless man; He could take away our sins, because He is omnipotent God. HMM