rational naturalism is impossible!

[Esquilax]

by that logic, developing true beliefs would not be a factor in lethal harm. P2 of the argument still stands.

It would be, if the false beliefs were harmful.

See, there's a reason children are more liable to believe authority figures when they're young; that's evolution in action. Parents teach their children things that are important; in an older, tribal civilization where this would be more useful, then fire being hot, and that animal being dangerous, would be true beliefs necessary for survival. Children that are more likely to accept this demonstrably true thing don't get burned or murdered by animals quite as much, while those that reject those true beliefs get killed.

Truth is all there is, and insofar as it regards the physical world that we inhabit, having a grasp on what's true is crucial for surviving. You can't believe a predator out of attacking you, for example.