I learned a long time ago that if I'm going to have a job anywhere and there are Christians, that I need to know about their faith better than they do so there will be no problems.
I typically do not engage in religious discussions with people of a different religious perspective, anymore. I choose to keep my religious affiliation secret and when a certain individual at the job insists on such discussions a polite "I'd rather not talk about that" seems to work fine for me. I've found that one cannot have an intelligent religious conversation with the majority of Christians out there today.
There are many that call themselves Christians, that do go to church every Sunday (or Saturday), but they really do not have a clue as to what the bible really says, and the same applies to other religions as well.
However the problem is not so much the religion, but the fact that they are not willing to think for themselves, they listen to others for what to believe. Also you are correct when encountering such people there is only one way to deal with them and that is not to talk about anything with them that requires much deep thinking on their part. After all putting forth anything that does not exactly fit with their beliefs, they will take it as a personal attack, but the educated people will think that God sent you to test their faith. Neither is a good place to put yourself.