“Suffering builds character” fails for suffering that destroys rather than builds: infants who die, dementia, torture that breaks the mind. James is talking about persecution endured by adults, not those cases.

Correct on both counts. James addresses trials that can be endured and grown through, not every kind of suffering. The soul-making response, associated with John Hick, is one Christian approach and has exactly the limit named here, which is why this case also offers presence, the resurrection, and free will rather than resting on character formation alone. No single response covers every case, and James should not be asked to carry more than he claims.