I was recently listening to a number of messages from the 2010 Fall Anabaptist Identity Conference, which offers a large number of downloadable MP3s. The message that I just listened to was Believer's Baptism - A Fundamental in the Separation of Church and State, which prevented a solid Scriptural defense of believer's baptism (although how any paedobapist can profess to defend this practice from Scripture is totally beyond me...)
Anyhow, from the message you see how the Anabaptists draw a strong distinction of church and state (which considering my growing disillusionment with all things political, this is something I'm finding more and more easier to agree with.) And on the topic of a state church, you can't have a true state church without infant baptism, compromising the requirements of membership in order to just bring more people into the church. On church and state, the question is asked: if all society is in the church, then where is the world, of which we are to be separate?
The church is to teach of the intention of making disciples. Who should be baptized? Disciples. We are commanded to teach all nations, a command observed everywhere, and our message is not to change until the end of the age. We should not teach based on assumptions or traditions, but on the Word of God.
Where in Scripture has Christ commanded infant baptism? He hasn't. Scripture says to repent and be baptized. Unless there is genuine repentance, no baptism. Paedobaptists will sometimes misquote Matt. 19:14, of “Let the little children come to me and do not hinder them, for to such belongs the kingdom of heaven", saying that Jesus here is allowing children into the kingdom of heaven via infant baptism. But if this passage is about infant baptism, and the disciples were familiar with this, then why did they object to the children going to Jesus? There is a distinction between "blessing" and "baptism". Additionally, how could they be baptized into the kingdom, if according to v.14 the kingdom already belongs to them?
Paedobaptists also misapply Col. 2:11, "In him you were also circumcised, in the putting off of the sinful nature, not with a circumcision done by the hands of men but with the circumcision done by Christ," in drawing an incorrect association with circumcision and baptism. Water baptism was never intended to replace circumcision, and while circumcision was done by the hands of men, baptism is about internal change, and operation of God alone. And if this parallel is to be drawn, it is notable that Abraham was circumcised AFTER his faith, not before. Additionally, appeals to traditions, in addition to being a fallacy of special pleading, run into a difficulty when you find traditions such as described in the Didache. Are infants really supposed to fast two days prior to baptism?
Believer's baptism is making a covenant before men, and being willing to give up everything (as the early radicals were when they defied the infant baptism traditions of the state church.) Infant baptism, on the other hand, includes sinners by design.