Your “Bible Christian” friends believe in baptism, but they do not believe in it as you do. Catholics understand baptism to be regenerative. It removes the stain of original sin and infuses sanctifying grace into the soul. Eastern Orthodox and many mainline Protestants think likewise, but Fundamentalists and Evangelicals disagree.
They say baptism is merely a sign that one has “accepted Christ as Lord and Savior” and therefore has become a Christian. It is the acceptance that matters. Undergoing baptism indicates to Christians that you are now one of them, but you would be one of them even if you never were baptized. Fundamentalists and Evangelicals call baptism an ordinance, a practice that Christ ordered his Church to perform, even though it does not effect a real change in the recipient.
This understanding leads to scriptural difficulties for those who think baptism does not rise above the symbolic. “He saved us . . . by the washing of regeneration and renewal in the Holy Spirit . . . so that we might be justified by his grace” (Titus 3:5–7). This “washing of regeneration” is baptism. It actually does something to us. It regenerates, says Scripture.
The conjunction of water and the Holy Spirit brings us to John 3:5: “Unless one is born of water and the Spirit, he cannot enter the kingdom of God.” The Catholic Church understands this combination to represent the water of baptism that brings to us the Holy Spirit, which is to say his grace. “Bible Christians,” avoiding the plain sense, say that Christians misunderstood this verse from the earliest years right up to the Reformation. Instead of “water and the Spirit” being read as a unit (baptism), they should be read independently: water (baptism) and the Holy Spirit (accepting Christ as Lord as Savior). Only the second is functional; the former is decorative—commanded by Christ but nevertheless not really doing anything to the recipient.
Turn to Acts 2:38, where Peter says, “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.” Notice the sequence: First comes repentance; then comes baptism—which effects the forgiveness of sins—and then, as a consequence of that forgiveness and therefore of baptism, comes the gift (the grace) of the Holy Spirit. This verse makes sense only if it is understood as saying that baptism is not a mere symbol. If baptism were just an ordinance and not a sacrament, why would Peter bother to include it in his instruction?
The head of the apostles is supported by Paul, who said to the Corinthians that “you were washed, you were sanctified, you were justified” (1 Cor. 6:11). By washedhe was not referring to the Corinthians’ bathing practices, because sanctification and justification are not dependent on hygienic practices. The verb meant that they had been baptized, and it was their baptism that brought them, for the first time, a state of sanctification and justification. Baptism changed them internally, spiritually, as it changes us.