Reformed Peadobaptists believe in the sacramental equivalence of Old Testament circumcision and New Testament baptism. They believe baptism has functionally replaced circumcision as the sign of the covenant. If you ask them to give a textual warrant for believing baptism as the Christian circumcision, then the verse that is often taken is Colossians 2:11-12. They argue that Paul here is equating the two and making baptism the Christian sacrament that correspond to circumcision.
Martin Salter, an MTh student at Oak Hill Theological College in London, has written an excellent essay verifying this claim made by Peadobaptists. The paper does not tackle Peadobaptism in its entirety, but demonstrates how the use of Colossians 2:11-12 by Peadobaptists, to prove the replacement of circumcision by baptism, is an illegitimate one.
In the paper, he first briefly considers the passage in its historical context to show that "the passage is primarily polemical and not sacramental". Hence Salter warns us to be cautious in "drawing firm conclusions regarding sacramentology" from these verses. Secondly, he examines Paul’s theology of baptism and circumcision to show that there is "a disjunction between physical and spiritual circumcision and it is the latter that is referred to in Col 2". Thirdly he goes for an exegesis of the verses and shows "how spiritual circumcision and baptism do not signify the same realities". He then summarizes his arguments and makes three conclusions. He makes an appeal to both sides of the debate, "to be cautious with this passage as it is mainly concerned with false teaching and not to teach the theology of baptism."
