Most American evangelicals are familiar with what Billy Graham does at the end of his preaching, calling people to walk to the front. Sometimes these are called “invitations.” Sometimes “altar calls.” When you look for something like this in the Bible there is no clear example… If you ask what the decisive, public way of taking a Christian stand was in the New Testament, the answer is, baptism. The message Peter gave in Acts 2 ended with the words, “Repent and be baptized in the name of Jesus Christ” (Acts 2:38). Our renewed conviction is that we need to regularly offer baptism as the decisive public way for people to respond publicly to the gospel.
John Piper