Some of it is pretty subtle so you'd have to know more about their own religious beliefs to figure it out. An insult really can go under the radar and nobody will notice.
Most likely your idea of a religious attack is different than mine though. I count Jains, Hindus, Moslems, Buddhists, RCs, Orthodox and Jews of all kinds ~ as well as Christians of all kinds ~among my own personal friendship circles, and to a degree, marriage and blood ties.
There's ways to get along. The first one is always assume that the guy making the attack may not know everything he needs to know about the target. The second is always assume the guy being attacked knows enough to not dwell on inanities and misconceptions regarding his own or the other guys religion.
I'll never forget when my cousin reminded me the Nazarenes had abolished their dress code and were now pretty much the same as Methodists. Now that was an embarrassment. I'm sure there are a million stories like that.
Did you realize the etiquette with burning candles inside religious buildings is pretty much the same with all religious groups? There's a sound reason for that!
You're right.
When it comes to the anti-Mormon, anti-Catholic and anti-atheist threads here, one thing you never have to worry about is missing the message due to excessive subtlety.........