“we declare to you what we have seen and heard so that you also may have fellowship with us; and truly our fellowship is with the Father and with his Son Jesus Christ.”
1 John 1.3 NRSV
This appears to be John’s purpose statement for his letter, along with v. 4. It’s about fellowship with the One who came in human form, so that all, accepting the gospel’s truth, could be one with God and with him.
To have fellowship with God, Christ, and his people, he must be proclaimed. What are you doing right now to proclaim Christ?