I'm referring here to Jess's reaction when she finds Brody's Koran in the garage after he confessed.

I mean, I could see if there was some religious reason, but I don't see many signs of overt spirituality or religious commitment in the Brody family and household. I think they went to church maybe once, as I recall that episode, it seemed more of an event for public consumption as any real devotion (and Islam seems a more satisfying devotional program than those austere Protestant services, IMO).

The only way I read Jessica's reaction is either abhorrence of the idea of Islam in its own right, or else a somewhat out of character consideration of the consequences to his political career. I know this season they are making her into more of a political wife, but she still seems to be in the Cinderella-at-the-ball stage, not yet into the calculating-advisor-and-invested-co-politician stage.