Many in the church today think of baptism as relatively unimportant or as a tertiary matter of conviction. Others understand baptism's importance but urge that we respect all of the historic traditions regarding baptism because Christians have been unable to reach any unified consensus on this question. Let me say that I love and respect many paedobaptists and that some of my greatest heroes of the faith have been paedobaptists. They are beloved brothers in the faith. But, I believe baptism is important and that the Bible is clear about how we should practice it. Here are some of the problems with paedobaptism.
1. The practice is never mentioned in the Bible. Paeodobaptism is neither commanded nor exampled in either the Old or the New Testaments. Some might respond to this by saying, "Of course it doesn't exist as an explicit command. Paedobaptism was an obvious implication to first century Christians." But, if that's the case, then the Acts 15 Jerusalem council would have been the perfect opportunity for the Apostles to explain the implication to those who evidently didn't get it. They could have ended the conflict over circumcision by saying, "Don't be so upset that circumcision is no longer necessary. Circumcision is changed to baptism! And, with baptism you may include your girl babies too!" The fact is that the exclusion of children from the covenant by the removal of the requirement of circumcision was very controversial, which is exactly what we would expect.
Some argue that the household baptisms in Acts are proof of infant baptism. But that's an argument of silence. The Bible never says there were infants in those households. In fact, the evidence seems to support credobaptism. Acts 16:31-33 says, "And they said, 'Believe in the Lord Jesus, and you shall be saved, you and your household.' And they spoke the word of the Lord to him together with all who were in his house. And he took them that very hour of the night and washed their wounds, and immediately he was baptized, he and all his household." Paul required faith from the jailer and his household (v. 31), and he preached to the whole household (v. 32). Only then, after requiring faith of the whole household and teaching the whole household, was the whole household baptized.
2. The Bible only explicitly requires the baptism of disciples. "Go therefore and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit, teaching them to observe all that I have commanded you" (Matt 28:19). By "make disciples" did Christ actually mean "procreate," or did he mean "go and make conscious followers of Me?" According to Scripture, if a person cannot "bear his own cross," and "come after" Christ, he "cannot be a disciple" (Luke 14:27). Jesus says, "Any one of you who does not renounce all that he has cannot be my disciple" (Luke 14:33). And, "if you abide in my word, then you are truly disciples of mine" (John 8:31). And, "You are My disciples if you have love for one another" (John 13:22). And, "By this is My Father glorified, that you bear much fruit, and so prove to be My disciples" (John 15:8). Can a child do these things? Do all the children of believers believe? Many paedobaptists see these things and realize that according to Scripture, the only people who really have a right to baptism are genuine believers. This leads to the next problem with paedobaptism.
3. Paedobaptism tends to baptismal regeneration. Or, at least it tends to the view that says the infants of believers are automatically regenerate. As soon as a paedobaptist actually crosses this line, he's very quickly moving away from the biblical gospel. Faith is often re-defined in moral terms such that it has no necessary intellectual content and does not consciously grasp Christ. Being a Christian is reduced to being a church member, no matter whether one consciously trusts in him personally. Because so many who are baptized as infants fall finally away from the faith, paedobaptists who believe in baptismal regeneration typically affirm that infants can be genuinely saved, united to Christ, and justified with a right and title to heaven, but then fall finally away from Christ and go to hell, thus denying the perseverance of the saints.
4. Paeobaptism tends toward the conflation of church and state. Some paedobaptists tend toward the view that sees Christianity as a religion of family, generation, and history, from below, rather than a religion of doctrine, faith, and personal conversion, from above. Paedobaptism is a religion of generational roots rather than of personal ideals, beliefs, and affections. You're a Christian if you're born into the family, no matter what you believe and no matter whether you delight in the God of Scripture for yourself. Thus, paedobaptism fits nicely with all theonomic visions of the union of church and state. As long as you're a good citizen, in good standing with the church-state or state-church, attending public worship, practicing the right forms of religion, obeying the laws externally, you're a Christian and have no reason to doubt your salvation. It is a "form religion" more than a "heart religion."
5. Paedobaptism is not supported by history. Paedobaptism was not standardized among Christian churches until the early 400's when Augustine defended the practice and normalized it. Prior to that, the majority practice was to delay baptism. A firm assurance of personal faith and final salvation was seen as the prerequisite of baptism, which is why many (wrongly) waited until they were on their deathbeds to receive the ordinance. The earliest clear didactic reference to baptism is found in the didache, and the reference affirms credobaptism, not paedobaptism.
6. Paedobaptism tends to undermine evangelism. Rather than encouraging children to come to Christ and to embrace him personally for salvation, some paedobaptists teach their children that they are already Christians and they already belong savingly to God and that God belongs to them. Paedobaptist parents sometimes give their children an identity of faith, teaching them that they already believe and encouraging them to continue in the faith to which they already belong. But, "continuing in the faith" sadly often only means "not doing anything that warrants church discipline." The consciences of these little ones are never pressed, and they are never warned that their souls may this very moment be in danger of judgment, if they do not believe personally in Christ for salvation. Such an orientation toward the faith can produce a cold, Pharisaical externalism in which these people "honor Me with their lips, but their hearts are far from Me."
7. Paedobaptism undermines "sola Scriptura." The formal cause of the Reformation was that "Scripture alone" determines our faith and practice. In the formal corporate worship service, this means that neither the pastor nor the church can require the congregation to participate in any form or element of worship not prescribed by Scripture. The ordinances of baptism and the Lord's Supper are defined and prescribed by Scripture, and they are vital parts of the corporate worship service, but the Bible never even hints that infants should receive the sign of baptism. Therefore, paedobaptists are not operating on a consistent "sola Scriptura" theology because they do what the Bible never requires them to do: they baptize their infants.
8. Paedobaptism fails to come to grips with biblical covenant theology. In the OT covenants, God was dealing with the geopolitical, theocratic, ethnic nation of Israel, but in the new covenant, believers are the children of Abraham (Gal 3:7), the Israel of God (Gal 6:16), the true circumcision (Phil 3:3), the royal priesthood (1 Pet 2:9), the holy nation (1 Pet 2:9), and the chosen people of God (Eph 1-2). In the new covenant, circumcision is a matter of the heart, rather than the flesh (Rom 2:28-29). The new covenant promises to forgive the sins of all its members (Heb 8:12), to write the law on all of their hearts (Heb 8:10), and to make them all know God, from the least of them to the greatest (Heb 8:11). And, according to Hebrews 8:9, unlike the old covenant, the new covenant is an unbreakable covenant. Just as circumcision was a sign of the old covenant, baptism is an ordinance of the new covenant, but since the new covenant is a believers only covenant, only believers have a right to the sign.
9. Paedobaptism tends to be internally inconsistent. Many paedobaptists apply the covenant sign of baptism to their children but deny the covenant sign of the Lord's supper to their children, until they actually profess personal faith in Christ. If their children are truly in the covenant, then why deny them the Lord's table? Surely all those who could ingest food in the old covenant, children and adults alike, took the passover meal. Paedobaptists exclude unbelieving adult spouses from the covenant, but in the old covenant, every household, including both husbands and wives, was in the covenant. Paedobaptists exclude their unbelieving household gardeners from the waters of baptism. But, in the old covenant, every male among you was to be circumcised, and that included servants. Paedobaptists require a profession of faith prior to baptism among adults, but no such profession was required in the old covenant. In the old covenant, the Israelites were known to circumcise an entire household/tribe by force. Paedobaptists require a profession of faith from parents before baptizing their children. But, that requirement is not revealed in either the old or the new testaments. Paedobaptists often refuse to baptize the children of baptized church members, if those baptized church members themselves have not professed faith in Christ. There is no revealed reason to do this.
10. Paedobaptism pretends "mode" is a legitimate category distinction. From a credobaptist perspective, mode isn't an issue at all. Biblical baptism means "immersion in water." Surely there are no "modes" of circumcision! Why should there be modes of baptism?