You could reframe this question as, “Are relationships hard?” The answer is sure. Some are easier than others, but sharing your life with another complete human is hard. You have to share, you have to give some things up, you have to take on things that don’t thrill you. In an interfaith relationship there are just an additional bunch of things to sort through.
If your partner comes from a vegetarian family, she may want to raise your children as vegetarians. This may involve you having meat just for you, or you eating meat outside the home. It means coming up with an explanation to the kids as to why YOU eat meat but they don’t. They may want a taste and your partner doesn’t want them to.
If you were raised in a family of sports enthusiasts and every season meant a sports team to follow avidly, you may be looking forward to taking your kids to a basketball, getting season tickets for your baseball team, signing your kids up for every sport possible. But your partner may have zero interest in sports and think they are a huge waste of time and money. He may resist even having you be focused on sports to the extent that your family found normal.
Religion and culture are simply another aspect of your life – and your identity – that will need to be negotiated. Let’s face it, negotiation is hard because it usually involves giving something up. Don’t look at religion differences as horrific divides that you should disguise and something else. Don’t bury them under false assumptions and hope they will not be there the next time you look. Jump in! Knowing what your differences are is the first step. Then you need to talk them through. Remember that I’m here if you need some help with how to keep the conversation rational and moving forward.
But don’t let anyone tell you that you shouldn’t have any issues; that’s simply not real life.