Too many churches today practice what they call "believer's baptism." I am sorry, but, biblically speaking, there is no such thing! It is biblical to baptize very quickly. On the day of Pentecost, 3,000 people were baptized moments after they heard Peter's Gospel sermon preached (Acts 2:41). The family of the Philippian jailer who heard the name of Jesus for the first time shortly after midnight, were all baptized by dawn (Acts 16:25-35). It is important to note that in the Greek, the belief is singular while the baptism is plural; the jailer believed and his entire family was baptized (including children). The Ethiopian Eunuch heard the Gospel and then minutes (at most, hours) later was baptized in ditch water by the side of the road (Acts 8:36-38). After hearing the word of the Lord from Ananias, Paul got baptized before breaking an absolute fast that he had observed for three days (Acts 9:9, 18-19).
Those who claim we should exercise caution as to whom we should baptize have no Scriptures to support them. Simon Magus was baptized in Acts 8:13, though he quickly proved how unworthy he was when he tried to buy the ability to give away the Holy Spirit. Peter essentially told him to go to hell (Acts 8:20). Likewise, Demas, who had been a fellow-labourer of Paul's, proved how unworthy he was when he left Paul for the things of this world (2 Timothy 4:10).
The reason people believe we should exercise caution when baptizing is because they do not understand the meaning and purpose of baptism. If they practiced baptism the way we see it done in the Bible, not only would they understand this, but they would also understand infant baptism. Except for the outward practice, everything about circumcision and baptism is exactly the same: Both are initiatory rites (Gen. 17:10-11; Matt. 28:19; Acts 2:38-39; 8:12-13); both signify an inward reality (Rom. 2:28-29; Col. 2:2-12; Phil. 3:3); both picture the death of the old man of sin (Rom. 6:3-7; Col. 2:11-12); both represent repentance (Jer. 4:4; 9:25; Lev. 26:40-41; Acts 2:38); both represent regeneration (Rom. 2:28-29; Titus 3:5); both represent justification by faith (Rom. 4:11-12; Col. 2:11-14); both represent a cleansed heart (Deut. 10:16; 30:6; Isa. 52:1; Acts 22:16; Titus 3:5-7); both represent union and communion with God (Gen. 17:7; Ex. 19:5-6; Deut. 7:6; Heb. 8:10); both indicate citizenship in Israel (Gen. 17:4; Gal. 3:26-29; Eph. 2:12-13; 4:5); both indicate separation from the world (Ex. 12:48; 2 Cor. 6:14-18; Eph. 2:12); and both can lead to either blessings or curses (Rom. 2:25; 1 Cor. 10:1-12; 11:28-30). Baptism replaced circumcision as the sign and seal of the covenant of grace. This fact is seen in Colossians 2:11-12 where Paul refers to "circumcision of Christ" as "baptism": "In [Jesus] you were also circumcised . . . having been buried with Him in baptism..."
You see, a person's baptism acts as a testimony for or against them, just as circumcision did. In the cases of Simon Magus and Demas, their baptism was a testimony against them that they were covenant breakers. If a church does not want to baptize infants, that is their choice, but do not claim that such a practice is not biblical based on your own ignorance and subjective opinion. "We must confess that some bring their children for this sacrament because of the sweetness of the ceremony, or because of the traditions of family and church, or even with the misguided expectation that somehow 'holy water' will magically protect their child from hell. Yet neither sentiment nor tradition nor superstition is sufficient reason for believers to bring their children to be baptized. And, thankfully, such reasons are not the basis of our church's practice. We baptize infants because we believe that the Bible teaches us to do so." (Bryan Chapell, Why Do We Baptize Infants?: Basics of the Faith, p.1)
Charles Spurgeon, commenting on Romans 2:28-29, wrote: "He is not a Christian that is one outwardly, nor is that baptism which is outward in the flesh; but is one inwardly, and baptism is that of the heart, in the spirit, and not in the letter, whose praise is not of men but of God." Baptism, whether by sprinkling, pouring, or dunking, is merely an outward demonstration of one's being dedicated to God for His purposes and uses. Yes, Scripture supports sprinkling, pouring, or dunking as baptism. Study the individual words out (baptizo, βαπτιζω; baptisma, βαπτισμα; baptismos, βαπτισμος; baptistes, βαπτιστης; bapto, βαπτω) and their usages and interpretations. How can you baptize a table (Mark 7:4)? Baptism does not save, does not regenerate, and does not mean the individual truly belongs to, or will belong to, the Lord. Baptism is not a public declaration of one's faith, as we have proven with Simon Magus and Demas, and we have witnessed rampantly throughout the North American churches.
When you were born, were you born as a full citizen of your country with all the rights and responsibilities thereof? Yes, you were. However, because you were young, you did not know of these rights and responsibilities and could not appropriate them. You had to be taught them. When you were older, you then either embraced them as your own or rejected them, which is treason and demands you leave your country. The same is true concerning circumcision and baptism. The son circumcised on the 8th day had no faith of his own. He knew nothing of the covenant promises and had to be taught it. As he grew, he could then embrace what he was taught by faith and appropriate the blessings unto himself, or reject what he was taught and appropriate the curses unto himself. The same is also true of baptism, which people would see and understand if they practiced it in accordance with what we see in the Scriptures.
What these churches should be doing when they baptize quick and biblical, is warning the people about the seriousness of the commitment they are making. Even Jesus warned potential disciples that following Him was a life-changing (even life-sacrificing) decision, telling them to count the cost of their decision. He said, "If anyone wishes to come after Me, let him deny himself, and take up his cross daily, and follow Me" (Luke 9:23). Frequently, Jesus' strong words seemed determined to drive people away who were less than whole-hearted in their decision to follow Him and obey His commands (Luke 9:57-62; John 6:53-66). When we evangelize, we should be doing no less. We should not be watering down the Gospel and presenting an easy-believism in order to gain numbers.
Baptismal candidates should be baptized quickly, but not without first being warned of the seriousness of sealing forever their decision to follow Christ.