Baptism is not just a symbol, as so many Evangelicals claim. According to the Bible, it is a marvelous grace--a great gift from God, which we do not deserve in the least and which washes away our sins, bestows upon us the Holy Spirit, grants us new life in Christ, and absorbs us into the Mystical Body of Christ, the Church. As even Martin Luther himself put it, baptism "works the forgiveness of sins, delivers from death and the devil, and grants eternal salvation to all who believe this, as the words and promises of God declare" (Short Catechism).
"Jesus answered [Nicodemus], 'Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.' After this [conversation] Jesus and his disciples went into the land of Judea; there he remained with them and baptized" (John 3:5, 22).
"And Peter said to them, 'Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children and to all that are far off, every one whom the Lord our God calls to him'" (Acts 2:38-39).
"Paul . . . came to Ephesus. There he found some disciples. And he said to them, 'Did you receive the Holy Spirit when you believed?' And they said, 'No . . . ' And he said, 'Into what then were you baptized?'" (Acts 19:1-3).
"And now why do you wait? Rise and be baptized, and wash away your sins, calling on his name" (Acts 22:16).
"Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life. We know that our old self was crucified with him so that the sinful body might be destroyed, and we might no longer be enslaved to sin" (Rom. 6:3-4, 6).
"For by one Spirit we were all baptized into one body--Jews or Greeks, slaves or free--and all were made to drink of one Spirit" (1 Cor. 12:13).
"For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus" (Gal. 3:27-28)
"In him [Christ] also you were circumcised with a circumcision made without hands, by putting off the body of flesh in the circumcision of Christ; and you were buried with him in baptism, in which you were also raised with him through faith in the working of God, who raised him from the dead. And you, who were dead in trespasses and the uncircumcision of your flesh, God made alive together with him, having forgiven us all our trespasses" (Col. 2:11-13).
"[H]e [God] saved us, not because of deeds done by us in righteousness, but in virtue of his own mercy, by the washing of regeneration and renewal in the Holy Spirit, whom he poured out upon us richly through Jesus Christ our Savior, so that we might be justified by his grace and become heirs in hope of eternal life" (Titus 3:5-7).