"In recent times, the way of being Christian that emerges from Anabaptism has been called the "believer's church." This term emphasizes the voluntary character of the church: people choose to join as believing adults rather than being born into a church community. Adult versus infant baptism signifies the two differing ecclesiologies- understandings of the church- with their contrasting kinds of entrée." -J. Denny Weaver (Becoming Anabaptist, p.163)
It is not for Anabaptists, or any man for that matter, to erect a dogma which suggests that voluntarism, reason, faith, or the understanding are qualities inextricably bound to the adult and irrevocably missing in the infant. One cannot say this, far less can one determine to exclude infants and little children from baptism on account of it. Faith in Christ (however one may define it; be it a work of the understanding or intellect, involving reason or absurdity etc...) is not a prevenient disposition that exists as a presupposition of adult humanity. When Anabaptists insist that humans by the mere fact of maturing become better equipped to decide on the nature of the Gospel, they fall into a clear Pelagianism (which teaches that there are qualities in men, untarnished by original sin, which may aid them in their justification before God). It is no coincidence here that the early Pelagians denied baptism to infants (cf. Augustine Contra Julian I).
Faith, and all that accrues to it in the justification of man before God (by which I mean reason or motivations of the will), is a GIFT FROM GOD. A free gift. It comes from God's free grace to the individual, and absolutely NO ONE has the right to question God's dispensation of this grace (Rom.9:20). It is nothing short of spiritual arrogance to deny the merits of God's Gospel to infants or say that God is capable of giving the gift of faith to adults but is incapable to do so for infants. Jesus rather says, "Suffer the little children to come unto me, for the kingdom of Heaven belongs to such as these." As I have said elsewhere, it is not adulthood with all of its reason and maturity that provides the best parable of faith but little children. They are the signs of Godly Trust in this godless world.
Infant baptism does not stem from some banal and useless thing called "church tradition" but from the authority of scripture and the proclamation of the gospel. It is in scripture that we learn to say:
Εκ στόματος νηπιων και θηλαζόντων κατηρτίσω αινον (Mt. 21:16)
In direct connection to the public confession of Jesus as Messiah by little children, Jesus includes infants (νηπιων) under the ordinances of God's praise. I leave it to Anabaptists with all of their devious sophistry to explain how infants can praise God without faith.
Naturally these criticisms can only apply to the Anabaptist who wishes to hold, for good or ill, to the scripture principle. I do not know of many in their circle of dark deeds today who wish to have anything to do with the authority of the bible. Inasmuch as believer's baptism figures in post-modern Anabaptism, it figures as a product of contemplative tradition rather than the authority of the Sovereign Lord of Heaven and Earth, who vows the destruction of the cosmos before the perishing of scripture.