1 John 1:3
 that which we have seen and heard we proclaim 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. (ESV)
Imagine for a moment that you have discovered a cure for cancer. And imagine that you your body was riddled with this terrible disease. After you applied the cure to yourself I can imagine that you would want other cancer victims to find the same triumph over the awful disease that you discovered. At least I hope that you are that kind of person!
Consider what the Apostle John has experienced. He walked with Jesus. He knew him more intimately than anyone else. He is referred to as the "disciple that Jesus loved." His life was transformed by Jesus Christ. He has forgiveness of sins and eternal life. You may remember that it was this same Apostle who wrote these words:
 “For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. (ESV)
The Apostle John knew this as a reality in his own life. And far more important than being cured from a disease, John was forgiven of his sinful nature. He had eternal life. He was now a partner in the eternal life, which is Jesus Christ. And John was one of those people that wanted to share this good news with others.
What John is proclaiming to us is an invitation to the same partnership with Jesus Christ that he had. And that partnership is like the partnership between God the Father and Jesus himself. Have you taken advantage of this offer? Have you believed in Jesus? John is extending the offer.