He must increase - his authority and influence among the people must grow. his doctrine shall continue to spread until it extends through all the earth.
I must decrease - “The purpose of my ministry is to point men to him. When that is done my work is done. I came not to form a party of my own, nor to set up a religion of my own; and my teaching must cease when he is fully established, as the light of the morning star fades away and is lost in the beams of the rising sun. This evinced John’s humility and willingness to be esteemed as nothing if he could honor Christ. It shows us, also, that it is sufficient honor for man if he may be permitted to point sinners to the Lord Jesus Christ. No work is so honorable and joyful as the ministry of the gospel; none are so highly honored as those who are permitted to stand near the Son of God, lead perishing men to his cross. Compare Daniel 12:3.