Religious tensions have existed far beyond and outside of NI for a very long time. Religion is important to people because for many, they feel it forms a fundamental part of who they are. It is also, (and this is key in precisely this instance) cultural, familial and geographical in the vast majority of cases.
It being a delicate topic because of history, is, to be honest, more the reason he should ask - it IS a delicate yet important topic. He has no idea your views, if you've not told him, so he must ask.
I can't see how you cannot understand that precisely because of the tensions, it would be very important, given the vast differences between people, their thoughts and ideas, and problems that have occurred, to find this out about someone you are dating. Perhaps he has done you a favour by ruling himself out.
Not wanting to date a religious, or not wanting to date a person of a particular faith, regardless of your heritage and religious tensions, is not bigotry.
I'm a steadfast atheist. I value my atheism and feel extremely strongly about it. I believe organised religion has been the veil for atrocities being committed throughout the world, and to control the masses. Therefore, I would not date a person of religion. Aside from the fact I could not ignore the intellectual incompatibility, either.
IF, and it's a very big IF, I were to consider a person of faith as a long term partner, it would largely depend on the faith. I would be more likely to choose a Christian partner, than a Muslim partner. The reason is perfectly valid - the cultural and familial aspects that I mentioned earlier. I am simply more likely to be able to relate to these aspects of the Christian faith than I would the Muslim faith.
It is never as simple as simply 'religion' - there's a whole load of baggage that come with it in the form of familial and cultural aspects that inevitably come into play. I speak from experience.
There's also zero point asking a board of people whom you know many of which will also not be in NI, and when you receive the answer you don't identify with, simply tell them they simply couldn't understand because they're not in NI. I think you're greatly undervaluing the intelligence and knowledge of a great number of women here. Mores the pity.