I think the point is that whatever predicate you fill in for "god", the implication is strictly speaking true in classical first-order logic (and probably many

I think the point is that whatever predicate you fill in for "god", the implication is strictly speaking true in classical first-order logic (and probably many other logical systems too). The pragma analogy is a good one. Whether there exists such a predicate that conforms to your conception of God or not is a separate (non-mathematical) issue. I think it's a bit like the surprise people show when they learn that in classical logic a false statement implies everything. Mathematics has strict formal rules, and it's important to leave aside your preconceptions of the semantics of various words like "implies" and "if" when engaging in it.