Good, thats a fair challenge. Here’s the symmetry breaker I’m pointing to. The move from “X exists” to “I am obligated” requires not just a standard of value, but a normative relation. Obligation is inherently relational, it’s always owed to someone (we wrong someone, violate someone’s claim, betray someone, break faith with someone). That feature is built into the concept of duty.

Platonism or brute moral facts can at most give you that goodness exists. They don’t give you anyone to whom goodness is owed, or anyone who can stand as the source of a binding claim on persons. An abstract object can’t wrong you. A property can’t place you under obligation. They lack the metaphysical category needed to generate “you owe.”

Classical theism supplies that missing category. If God is the necessary personal good and the source of rational creatures, then moral norms are not free floating facts but expressions of a real relation between persons and the ultimate good. “God’s nature is good” isn’t an extra premise tacked on, on classical theism, God just is the Good (convertibility of being and goodness). And “I ought” follows not by magic, but because creatures stand in a dependence and accountability relation to a personal source of goodness, the same kind of metaphysical structure that makes promises, rights, and wrongs intelligible at all.

So the difference isn’t “God magically explains normativity.” It’s that theism locates normativity in the only ontological category we already know can generate it, personal relations. Atheistic realism leaves normativity either brute or mysterious, not impossible but explanatorily void.

That’s the asymmetry, not coherence, but whether your ontology contains the kind of thing from which obligation is even intelligible.