Luke mentions a specific period of time, by mentioning the governmental leaders of the time, in which, John came into the district, around the Jordan, preaching a baptism of repentance for the forgiveness of sins. The people came to John for baptism and he preached to flee from the wrath to come and bear fruits in keeping with repentance. Though the people wondered if he was the Christ, John himself, said:
As for me, I baptize you with water; but One is coming who is mightier than I, and I am not fit to untie the thong of His sandals; He will baptize you with the Holy Spirit and fire. His winnowing fork is in His hand to thoroughly clear His threshing floor, and to gather the wheat into His barn; but He will burn up the chaff with unquenchable fire. (Lk 3:16, 17)
Like all that represented the old covenant, the law and the prophets, Isaiah and Jeremiah who prophesied Messiah (Christ) and a new covenant; John proceeded the Christ in ministry.
The law prepares the soul to receive the Christ. Not to say that one should clean themselves up before coming to Christ, but the law shows one need of Christ. Like the apostle Paul said, “The law brings the knowledge of sin.” (Rom 3:20) The law can bring us to Christ but no further. The law does not justify, it just shows us that we are guilty. It is God who justifies, and he is just to justify all in Jesus Christ.
Jesus came to be baptized by John before beginning his ministry. At Jesus’ baptism, God was present in the persons of the Father and the Son and the Holy Spirit; one Devine being in three persons. Jesus is, therefore, fully God and fully man in one person. This is a mystery and yet revealed. Jesus was supposed, the son of Joseph, whose lineage dated back to king David, to Abraham, to Adam, but he preceded these patriarchs; he is the Son of God. Jesus both preceded the first man Adam and came after his supposed father Joseph.