What does John 3:29 mean?
John the Baptist was clear, right from the beginning, that his ministry was all about leading people to Jesus (John 1:23; John 3:28). So, when people tell him that Jesus is attracting more attention, he is not concerned. In fact, he is joyful—this is what he was called by God to do, and he's seeing it happen.Wedding terminology is common is the Bible. God is often pictured as a groom who takes Israel, or His people, as a bride (Isaiah 54:4; Jeremiah 2:2; Hosea 2:19). The best man at a wedding is not meant to be the center of attention. Of all of the men involved, the groom is supposed to get all of the applause. The best man's role is to help the groom, to be his advocate, and his friend. When the groom has his bride, the best man is joyful. He's not jealous or angry, because that outcome is exactly what he wanted in the first place.
In this way, John the Baptist has acted like a best man for Jesus. Now that Jesus has come on the scene, the Baptist is happy to see Him succeed. Verse 30 is the logical end result of this change. If people are going to follow Jesus, they can't follow John the Baptist, as well. In order for the Baptist's mission to succeed, he must lose popularity and fame, and Jesus must gain it.