<< Can you point me in the direction, scripturally, of the 3 prongs to which you refer? >>
Firstly, if anyone else has responded to Jay, I apologize for my lack of interaction with has been written. It's been a long day, & I haven't been able to look at the mailbox which receives my CRTL mail, and now I'm at home, I can't access it. Hopefully this isn't too much of a repeat of what's been going on today.
Secondly, I'll try to keep this brief. I'm a firm believer in toe-dipping when it comes to examining big concepts; diving into the deep end can lead to drowning in the detail. So just a few points, then, on the understanding that this is a tiny fraction of the complete argument. Please don't infer from the brevity that I believe I have proof-texted my way to a conclusive position.
(1) Continuity of the covenant.
Baptism question aside, this is crucial for a good understanding of scripture. Any book of the bible you care to mention falls into place when it is seen against the background of the continuing covenantal dealings of God with his people. Until recently, my understanding of this issue had largely been guided by the writings of Anglican apologists for covenant theology. A far better job has been done by Presbyterian O Palmer Robertson in _The Christ of the Covenants_ (recommended to me by Robert Lotzer, who is a member of this list - thanks Robert). This book is a must read.
(a) Consider Ezekiel 37:24-26. This is lovely. It is the Sovereign LORD speaking:
"`My servant David will be king over them, and they will all have one shepherd. They will follow my laws and be careful to keep my decrees. They will live in the land I gave to my servant Jacob, the land where your fathers lived. They and their children and their children's children will live there forever, and David my servant will be their prince forever. I will make a covenant of peace with them; it will be an everlasting covenant. I will establish them and increase their numbers, and I will put my sanctuary among them forever...." (Ezekiel 37:24-26)
Notice how the Abrahamic, Mosaic, and Davidic covenants find their consummation in the new covenant? There is continuity between them.
(b) Consider Galatians 3:16. It's a golden key...
The promises were spoken to Abraham and to his seed. The scripture does not say "and to seeds", meaning many people, but "and to your seed", meaning one person, who is Christ. (Gal 3:16)
If a person belongs to Christ, then he is part of which covenant? He is an heir according to which promise? (Gal 3:29 answers this).
Continuity of the covenant, then - a tiny introduction.
(2) Continuity of the church.
Romans 11 talks of Gentile believers being grafted into the same tree as Old Testament believers. The continuity of the church is so important that Peter even dares to describe the Christian Church in terms of OT language (1 Peter 2:9). Luke describes the Jews wandering in the desert as the ekklesia (Acts 7:38).
Again, just a taste.
(3) Continuity of the sign.
How about Colossians 2:11-12 for starters? I won't elaborate, because I'm trying to be brief.
-------------- Now, the point is that the visible church has always included the children of believers. When the sign of covenant membership was the sign of circumcision, the children of believers received it. Given the continuity of the covenant, the continuity of the church, and the continuity of the sign, should not the children of believers still receive the mark of membership in the visible church?
If the new covenant is entirely discontinuous from the old, then no. If the NT church is separate from the OT church, then no. If baptism and circumcision do not overlap in what they signfy, then no. But none of these is the case.
As I say, just toe-dipping: not a comprehensive defence. Hope the water feels warm to you, Jay.