He has to say it, because he has to know that Clark knows. Nearly shattering his hand flailing at him and only feeling bad about being violent notwithstanding. When Clark had first returned from the grave, and nearly fried Batman where he stood, Bruce's immediate concern was that when he came back to himself, he'd be devastated that he'd done it.

(In front of half of Metropolis, anyway. Bruce had accepted, the second Clark turned to him, that he had a right to end his life if he felt it was justified. The world needs Superman, not Batman.)

Bruce closes his eyes.

"How do you do that."

Clark is so much better at this faith thing.