If you had a chance to prove Jesus really lived on the earth, what evidence would you give? A miracle? A sign? A revelation? A dream? Well, in 1 John 1:1-4, John gives us evidence that is much more concrete than that. He writes:
That which was from the beginning, which we have heard, which we have seen with our eyes, which we looked upon and have touched with our hands, concerning the word of life was made manifest, and we have seen it, and testify to it and proclaim to you the eternal life, which was with the Father and was made manifest to us (vv. 1-2).
He doesn’t appeal to some kind of ecstatic vision or religious experience. John is saying, “I saw Jesus with my own two eyes. I touched him. I talked to him. I walked the hot desert roads of Israel with him. I sat at the foot of his cross weeping with his mother while I watched him die. And I saw the empty tomb before he appeared to me in the flesh. This man is real and he is co-eternal with God the Father since eternity. This man is God.”
John’s not playing games. And he’s not writing this to be a fun-sucking, religious kill-joy who is ready to condemn sinners. Instead, he writes to obtain the highest joy — the joy of having fellowship with God and his people: “We proclaim [this] also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ. And we are writing these things so that our joy may be complete” (v. 3-4).
If Jesus had never come to Earth, complete joy and fellowship with God and others would not have been possible. There would only have been dead religion and subjective experience. John’s not interested in that, and neither am I.