My parents do. As do I. I don't even believe in Christianity, and it's not a struggle to do so.
What does it matter, anyway? People are going to take offense to that because you are basically challenging the fact that they believe in their religion. It's not a religious topic, nor is it something that needs to be discussed. 'Throwing your religion away' and becoming a variant of sexual orientation that may not agree with the bible are two completely different things. Many people who are Christian believe that it's okay for homosexuals to exist. Maybe if you didn't want to offend anyone you shouldn't have posted.
Anyway, religion isn't the topic.
I hope you have a long lasting relationship with your partner. I hope you two enjoy eachother's presence and cherish the moments you spend!