The readings for the Baptism of our Lord (the first Sunday after Epiphany) are taken from Isaiah 43:1-7; Romans 6:1-11; and Luke 3:15-22.
The Baptism of Jesus marks the beginning of His three and a half years of public ministry and establishes the sacrament of Baptism as a work of God that is effective—as God’s Word always is (Isaiah 55). Isaiah describes passing through the waters. Isaiah precedes and follows that reference to baptism with many promises of God: He has redeemed us; He has and continues to love us. Notice the reference to passing through the fire, as the three men in Daniel were able to do because the Son/Word of God was with them.
Paul spends most of Romans 6 talking about baptism. The essence of biblical teaching about baptism has to do with a life immersed or at least awash in God’s Word, which is described as living water (see Jesus with the woman at the well in John 4). A life immersed in God’s revelation surrounds us with the Word and Spirit that regenerates and energizes our soul and holds our corrupt human nature under the truth and law, which helps keep it subdued until God relieves us of it when it dies. Our life in God’s Word joins us to the life of Jesus, especially by way of thinking about things the way He does (see Colossians 3:1ff).
Luke records the baptism of Jesus. Jesus lived His whole life, from conception to ascension, as a substitute for ours. Jesus bore under the law everything that is wrong with our life, from conception to the death of His body by crucifixion, which is what the law demands. The physics of life in the living water of God’s Word changes everything. Through the life of Jesus, God has opened heaven to us and declares that we are His beloved children with whom He is well pleased!