Let me preface my comments by letting you know that over the last few months I’ve come around to the paedobaptist position from what I would previously have called a “Reformed” and “Covenantal” Baptist position. I had first learned Covenant Theology from Richard Barcellos, and had read through his writings on the subject, as well as those by Welty, Malone, Tombes, Coxe, etc., and every Reformed Baptist Theological Review to date. I say that to make it clear that I am at this point arguing against my former self just as much as I am against Welty.
Welty does a good job of identifying circumcision as one of the central elements in the debate, but he falls short in that he misconstrues the meaning of circumcision. If you take a wrong turn at the very start, then whatever you do subsequent to that is of no consequence.
He does the same thing that I did when he deals with the paedobaptist argument regarding the meaning of circumcision ““ he acknowledges it, and then promptly ignores it. He cites a hypothetical response from a paedobaptist on page 7:
"…circumcision points to inward cleansing (Deut 10:16, 30:6; Jer 4:4, 9:25-26; Ezek 44:7; Rom 2:28-29)"
and follows it up by admitting that this “calls for an examination of these other texts”, but then proceeds to hand waving to dismiss them without the called for examination. Welty says, as you quoted,
"But one might as well argue that since OT sacrifices signified spiritual realities, we have warrant for continuing their use today. Clearly, we do not."
This completely ignores the fact that we have explicit NT texts abolishing the OT sacrifices, which is not the case for applying the covenant signs to children. But not only is the reason for his dismissal of the texts terribly flawed, but in place of them he goes rooting around in Genesis 17 and elsewhere making bad inferences, and then bases much of his subsequent reasoning on that misidentification of the meaning of circumcision.
Also, his argument on page 6 about the “historical-redemptive significance of Abraham’s circumcision” being prophetical of the inclusion of the gentiles is rather far-fetched; I was surprised to see him try and make this argument. Again, he ignores the explicit reason given in scripture for Abraham’s circumcision ““ “it shall be a sign of the covenant between me and you” (Gen 17:11) and tries to back out from Romans 4 a wrongly inferred meaning. Paul is not at all saying “this is what circumcision means“, he is making an argument from the circumstances of Abraham’s circumcision to prove his point that possessing the sign of the covenant is not necessary in order to possess the substance of the covenant, and that is exactly what the Judaizers were arguing ““ no circumcision, no salvation (see WCF 28:5).
On page 8 he says:
"It is quite plausible to hold that circumcision was specifically applied to the seed of the OT people of God in virtue of this prophetic significance of the sign itself."
Again, he is arguing on the basis of “it is plausible for us to hold that circumcision means this”, over and against the texts of scripture that say “circumcision means this”. This was my favorite trump card, the argument from “prophetic significance” or “typology”, which at the end of the day is speculative at best. I could use it to dismiss any argument from the Old Testament that I didn’t like, but in reality it’s just an ipse dixit.
Welty also makes a few faux pas that take away from the credibility of his arguments. For instance, he accuses paedobaptists of using “abbreviated or paraphrased “˜citations'” (footnote 3, page 4), but he then proceeds to do the same thing on page 10, where he throws out his own abbreviated citations of “circumcision is nothing” (1 Cor 7:19), and “neither circumcision nor uncircumcision means anything” Gal 5:6), without addressing the context or the sense in which Paul meant those statements to be taken, or reconciling them to other places where Paul says “circumcision indeed is of value if you obey the law” (Rom 2:25) or “Then what advantage has the Jew? Or what is the value of circumcision? Much in every way”¦” (Rom 3:1-2). When I quote snippets of these texts the way he does with the others, I can make them appear to say the exact opposite of what Welty tries to make the others say.
To sum up, Welty dismisses explicit biblical texts on the meaning of circumcision in favor of his own misconstrued meaning of it, and bases his reasoning on that. His error was the same as mine was; I was ignorant of the spiritual meaning of circumcision, and hence made up my own meaning of it to fit with my theology. Any subsequent arguments based on that premise are all invalid.