Back to the OP, I find it to be an interesting ethics question - it brought me up short. If my clients were "bland" Christians (e.g. Presbyterians - which I can tease because my parents are), I'd probably let it go. But if the clients were Westboro Baptists I might bring it up - I feel as though I *ought* to tweak folks like the WBers, it would be cowardly not to.