The "beloved physician" and companion of Paul introduces readers to John the Baptizer, a prophet who warns crowds of people about God’s coming judgment, calls them to perform justice in their interactions with one another, and performs a “Jesus was baptized (literally, "dipped") in the Jordan River by John the Baptizer, at which time he was acclaimed from heaven as God's Son, the Beloved. Much later baptism became one of the sacraments of the Church, the action by which a person is incorporated... of repentance.”
Of all the Gospels, Luke provides the most detailed description of John the Baptizer’s ministry. Luke connects John’s message to the book of Isaiah, son of Amoz, who prophesied in Jerusalem, is included among the prophets of the eighth century B.C.E. (along with Amos, Hosea, and Micah)--preachers who boldly proclaimed God's word of judgment against the economic, social, and religious disorders of their time. (quoting Isaiah 40:3-5 in vv. 4-6). John issues pointed warnings about God’s impending judgment, expressed in images familiar from the Jewish Scriptures (the Christian Old Testament) (vv. 7-9, 17; see also A tax collector who became one of Jesus' 12 disciples 3:7-10, 12). He instructs people to practice basic justice (vv. 10-14, material that appears only in Luke’s description of John). He promises that one “more powerful” than he is on the way (vv. 15-17). This brief sketch of John continues the tendency established in Luke 1-2, where John and Jesus is the Messiah whose life, death, and resurrection are God's saving act for humanity are both closely associated (part of the same work on God’s behalf) and clearly distinguished (Jesus is the Christ, and John goes before him “to prepare his ways,” according to 1:76).
Luke introduces John, in vv. 1-2, in a manner recalling the prophets of the Old Testament and historical writings of the Greco-Roman age. The rulers of the day are identified, from the Roman emperor down to more regional, local officials. The scene is set: from a Jewish perspective, this is an atmosphere of foreign occupation; yearnings for the Lord to deliver the people of God must be in the air. Luke draws additional attention to the tense political setting later, in vv. 12-14, by reporting John’s words to tax collectors and soldiers (two of the most visible, constant reminders of the The region we today call Palestine and Israel was under Roman rule during the time of Jesus and the early church. The Roman Empire was in its ascendancy during the first century, making it the most powerful political and military force on earth.). John admonishes these groups against using their positions for economic exploitation.
“The word of God” comes to John, who preaches and calls people to repentance. This is his role in making “ready a people prepared for the Lord” (Luke 1:17). The call to repentance is explicitly linked to a washing, a “baptism” (the word simply means “dipping”) for forgiveness of sins. In undergoing John’s baptism of repentance, people commit or recommit themselves to God and, as a result, should “bear fruits” in living lives that manifest God’s intentions. John was not the only Jew of his day promoting a lustration rite (a purification ceremony), but his stands out in that he immerses others in water (as opposed to people washing themselves). His activity attracted large numbers of people. Certainly Jesus’ close association with him—an association that this Gospel strongly emphasizes in Luke 1—would have attracted people to Jesus, even as it would have repelled others.
Luke names John’s message as “good news” (or “gospel”) in 3:18, indicating it aligns fully with what Jesus and his followers will later proclaim in this Gospel and the book of Acts. Not everyone hears it as good news, however; King over Galilee who executed John the Baptist and mocked Jesus before the crucifixion., the ruler of Galilee and Perea, responds to John’s criticisms by arresting him. Herod will later execute John (Luke 9:9). In Luke and Acts, proclaiming “good news” about judgment, repentance, justice, and forgiveness in this political climate proves over and over again to be dangerous business.