[Disclaimer: I totally lived in sin with my boyfriend/FI before we were married in a Catholic ceremony, so any hypocrisy I point out is also my own.]
This is the second post I’ve answered in 24 hours seeking advice on how to thwart religious teachings and/or lie to a religious officiant!
I think it’s important to note the hypocrisy of the situation- you want to be married in a religious ceremony, but you don’t want to abide by the teachings of the religion!
I know you say you shouldn’t have to take his advice on this, but he has the right to refuse to marry you if you don’t. You are blatantly disregarding his (and supposedly your) religious teachings by "living in sin". (Mind you I also lived in sin, so I’m totally playing devil’s advocate here)
The way my husband and I got around this was that we had a pretty inexperienced priest who didn’t even ask! I think he was more caught up in the fact that my FI wasn’t Catholic. However, I was petrified of what would happen if the priest found out (he never did- or if he did, he didn’t let on that knew). Since avoiding the topic or telling a white lie isn’t an option anymore…
You could outright lie to him. (Obviously not something that you really want to do to a man of the cloth)
You could ask for his advice- tell him that you discussed it at length but that living seperately isn’t something you want to do. Ask him why he feels it’s important for you to live apart. Ask what the benefits would be and if he can think of anyway you could still reap those benefits while living together.
I’m guessing the answer is sex- as in, religion says you shouldn’t be having any! Perhaps he will allow you to compromise and abstain until the wedding? Ask him if there is something you can do to show your commitment to preparing yourselves for marriage without living seperately.
Keep in mind that if you compromise, you will have to make a sacrifice (or lie about making one) in return for him overlooking your cohabitation. And generally, a good compromise means nobody’s happy.
Otherwise- I’m thinking you may have to find another minister or have a secular ceremony. That’s kind of just the price you pay/risk you take if you want a religious ceremony but disagree with aspects of your religious prohibitions.