NOTES for Jo1 1:1-10
The beginning of the letter echoes the beginning of the Gospel written by John, which in turn recalls the beginning of the book of Genesis. At first glance, there is also a difference: there the foundations of the world's order are narrated, while here John reminds us that he is a witness of what he is writing about. But his witness is not reduced merely to a formal confirmation of facts. It consists in proclaiming that John knows the essence of what he saw: the coming into the world of the Source of life. The purpose of the letter is precisely that people may have fellowship with Him and with one another, not secular socializing or the bustle of "hangouts," but an inexpressibly mysterious union with God and with brothers who have also entered into union with Him and with one another.
The criterion of the authenticity of such union should be the qualitative changes taking place in people, and not only formal membership in the brotherhood. But is there not a contradiction in saying that those who walk in the light cannot remain in darkness, if no one can claim to have no sin?
No, because it is only thanks to the light that one can see one's own sinful darkness. Having seen it, one should not hide back in the darkness, but on the contrary, go boldly with repentance toward the light that delivers from sin.