If both people genuinely respect each other and have a healthy, loving relationship, it can certainly work. However, one major downside is that you can't fully share the most important part of your life, your faith. You may never be able to discuss spiritual matters together, go to church as a couple, study God's Word or worship Him together.
Over time, that can become a real source of sadness and frustration, especially if your relationship with Christ is central to your life. It doesn't mean the relationship can't be happy, but it can be a significant challenge in the long run.