Having grown up in the Southern Baptist context and later the more Arminian Church of God (Anderson, IN), I have vivid memories of those altar calls. Particularly, in high school in the Church of God, our youth group Wednesday evenings featured altar calls with the same kids going up weekly “deciding” to rededicate and/or get saved again. The emPHAsis was always on the decisional aspect of one’s relationship to God. It has been a slow journey for me to release that bad theology…and I have never heard one put it quite this way that folks feel they “are in charge” of their relationship to God. Thanks be to God this gospel clarity is sinking into my thinking more and more.
As your colleague Chad Bird points out, metalepsis matters: Shechem (Nablus) is in the valley between Mount Ebal and Mount Gerizim. From Gerizim 6 tribes had blessed (Simeon, Levi, Judah, Issachar, Joseph, and Benjamin) From Ebal 6 tribes had cursed (Reuben, Gad, Asher, Zebulun, Dan, and Naphtali) To CHOOSE BETWEEN has a literal geographic meaning here. As you suggest, this is not the first time Israel agreed to a covenant that no one is capable of keeping.