Sections 28 through 33 in Go and Make Disciples address the question “Why Evangelize?”
The bishops give a straightforward answer: Jesus told us to do it.
Starting from the mission statement of Matthew 28:18-20 (in GMD 28), we are given the Scriptural basis for evangelization:
The Lord commanded us to evangelize because salvation is offered to every person in him. More than a holy figure or a prophet, Jesus is God’s Word,(John 1:1; 1:14) God’s “very imprint,”(Hebrews 1:3) the power and wisdom of God.(1 Corinthians 1:24) He is our Savior. Becoming like us and accepting our human nature, (Philippians 2:7) he addresses in himself, in his death and resurrection, the brokenness of our lives. He suffers through our sin; he feels our pain; he knows the thirst of our death; he accepts the limits of our human life so that he might bring us beyond those limits. “[H]e humbled himself, becoming obedient to death, even death on a cross. Because of this, God greatly exalted him! . . .”(Philippians 2:8-9)
Jesus is the central figure, inspiration, and source of Christian evangelization. And he tells us to do it.
Catholic Sensibility 