We were both raised in different religions.?

My girlfriend and I were raised into different religions. She was born into the Jehovah Witness society and I was raised along Christianity. We are both fairly new in our relationship. (Always been good friends). She was shunned in her religion after taking on a serious relationship in her HS years and now just has an empty view to faith and I don't really know what her faith is anymore. We both respect each other and I'm careful not to speak of religion. But how can we try to attend a church together without creating an uncomfortable setting. I'm just trying to add a religious foundation to our relationship.