John the apostle wrote about faith and reassurance in Jesus.
Near the end of his gospel, the Apostle Thomas is recorded as expressing His faith when seeing the risen Lord Jesus saying, “My Lord and my God!” Jesus said to him, “Because you have seen Me, have you believed? Blessed are they who did not see, and yet believed.” Therefore many other signs Jesus also performed in the presence of the disciples, which are not written in this book; but these have been written so that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name” (Jn 20:28-31).
John’s general epistle began with the same theme. “What was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and touched with our hands, concerning the Word of Life—and the life was manifested, and we have seen and testify and proclaim to you the eternal life, which was with the Father and was manifested to us—what we have seen and heard we proclaim to you also, so that you too may have fellowship with us; and indeed our fellowship is with the Father, and with His Son Jesus Christ” (1 Jn. 4:1-4).
We know Jesus through those that knew Him. Evangelism is still people coming to know Jesus through others who knew Him first and that He lives though. Let us proclaim Jesus by telling of Him and demonstrating His life in ours (Gal. 2:20; 2 Cor. 4:10,11).