I remain confused as to why God in being ‘more generous’ has actually also made it ‘more ambiguous’. Wheras under the Old Covenant the command (and its benefits) were explicit, under the New they must be deduced by inference….
Well, I’m not sure I can address your question completely perhaps because I don’t agree with the assumptions on which it’s built—I’m not sure I understand the question fully.
1. In this context, I might not have written about the “old covenant” or “old testament” quite the way Liam did. He was using the term, as we often do, in the broad sense. Strictly speaking, however, the “old covenant,” in the narrow sense, refers to the Mosaic (including David) covenant that began at Sinai and ended at the cross. In that sense, then, infant circumcision was not strictly an “old covenant” rite.
2. Circumcision was typological, i.e., it pointed forward to Christ’s death on the cross.
4. I think the assumption that you’re making that confessional paedobaptists have rejected is that the advent of the new covenant requires that infant initiation be stated explicitly. That assumes that there was more discontinuity with Abraham than there was and that assumes that Abraham is not the paradigm. So, there is a web of assumptions that must be untangled.
We begin with the conviction that Abraham Was Not Moses. Everything that was distinctly Mosaic has been fulfilled and abrogated. Infant initiation was not Mosaic. It was Abrahamic. That makes a big difference. Yes, there were typological elements under Abraham, circumcision being one of them but was infant initiation one of them? We say no because the promise is: I will be a God to you and to your children. Where did that promise change? Assuming continuity with Moses may be problematic but assuming continuity with Abraham is not because of the fundamental nature of the promise. It was explicitly re-stated in Acts 2:39. That’s not an inference. If the promise is to covenant parents and to their children then, of course, there remains a pattern of initiation into the visible covenant community of believers and their children. Peter didn’t have to say, “yes, we’re still initiating children into the new covenant community” because he already had in Acts 2:39. He would have needed to be explicit to revoke the Abrahamic promise. According to Paul in Romans 4 and in Gal 3-4, the Abrahamic promise wasn’t revoked. It was foundational. The Mosaic was an addendum to the Abrahamic.
5. Finally, according to the NT itself, the new covenant is new relative to Moses, not to Abraham. Check out this essay.