If we say that we have no sin, we deceive ourselves, and the truth is not in us.
You remember Micah's prophecy of the birthplace of Jesus, "And thou Bethlehem, though thou be little among the provinces of Judah, yet out of thee shall come He who is to rule my people Israel, whose going forth have been from old from everlasting." The eternal life always existed. In the beginning the Word with God, was God. "But the Word was made flesh and He dwelt among us and we beheld His glory as of the only begotten of the Father full of grace and truth" ( John 1:14 ). Jesus, the eternal Word, Jesus the eternal God, became flesh and dwelt among men and John said, "We saw Him, we stared at Him, we heard Him and we touched Him. And that which we saw, and that which we heard we now bear witness to you." The eternal life that was with the Father and was manifested unto us. That eternal life, it's a, not just duration; it's a quality of life, as well as duration.