NOTE: I have modified some of the language in the answer to this question in alignment with my own Baptist convictions.
Question 44: What is baptism?
Answer: Baptism is immersion in water in the name of the Father, the Son, and the Holy Spirit; it signifies our death and resurrection with Christ, our cleansing from sin, and our commitment to belong to the Lord and to his church.
Does baptism save us? Although we may be tempted to answer that question with a quick "yes" or "no," the biblical answer is actually more nuanced. Let's take a look at a key verse in the New Testament that clearly links baptism to salvation. In 1 Peter 3:21, the apostle Peter writes, "Baptism, which corresponds to this [water of the flood of Noah's day], now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ." Peter explicitly says here that baptism saves us. Case closed, right?
Actually, take a closer look at what Peter says. Yes, baptism saves, but how? First, Peter specifies how it does not save: "not as a removal of dirt from the body." The physical act itself, in other words, carries no inherent saving power. There is nothing about being immersed in water that, in and of itself, accomplishes the work of God's salvation in us. But then Peter specifies how it does save: "as an appeal to God for a good conscience." In other words, baptism saves us as an act of faith by which we seek forgiveness of our sins through the gospel. For Peter, baptism represents faith going public, and it is the faith element that is the means of our salvation.
Often in our discussions about baptism, our minds leap to exceptional circumstances. "What if someone believes the gospel but then dies before he can be baptized? Is he still saved?" Those questions have their place, but they should not dominate our theology of baptism. The biblical teaching ties baptism very closely to conversion, and thus Peter can speak of baptism itself as a saving ordinance because he associated it with the initial coming to faith of an unbeliever. Yes, we must maintain that salvation is by faith alone, and in the event that someone is unable to be baptized, faith alone will save him. But the normal New Testament pattern is that faith issues forth in public form in baptism. We are accustomed to speaking of baptism as the first act of obedience after conversion, but we should speak of it more as the culmination of conversion, or the public identification of a believer through a public identification with Christ in his death and resurrection. Consequently, anyone who claims to believe in Christ but willfully refuses baptism raises doubts about the quality of his faith.
If you think about it, evangelicals have had public faith rituals for generations. How many people have associated the moment of their salvation with walking an aisle, praying the sinner's prayer, or raising a hand in response to a preacher's invitation? There is not necessarily anything wrong with these actions, and I do not call into question the sincerity of those who were converted in association with such actions. But we should seek to conform our practice more closely to Scripture, and in the New Testament, faith goes public not by any of these actions, but by baptism. A person can be saved by faith in a moment without any visible actions on his part. But if that faith is real, it will inevitably manifest itself by the reception of baptism, the act ordained by Jesus for his followers to identify themselves with him. And in this way, baptism saves you, according to the apsostle Peter.
Suggested passage for personal or family reading: 1 Peter 3:8-22. What are Peter's larger concerns in this passage? How does baptism fit into his point? How are the waters of the flood similar to our baptism? How is the resurrection of Jesus Christ similar to Noah's ark?