Tannersimon:
I have questions though as her religion is non-denominational. I’m wondering what the big differences are and if there may be problems we may run into through this.
It’s difficult to know because non-denominational churches are by definition outside of any larger church organization. If, for example, her church was Assemblies of God or Presbyterian or Lutheran or Southern Baptist, etc. it would make it much easier for us to pin down what she believed.
But a non-denominational church is a “lone wolf” so to speak. It isn’t a member of any of these larger groups, and so it doesn’t have to adhere to any written confession or doctrinal statement.
Typically, however, when someone says they are a non-denominational Christian, I think of some form of evangelical (because most non-denoms are evangelical in their beliefs). They could be similar to Baptist without calling themselves Baptist or Pentecostal/charismatic without calling themselves Pentecostal/charismatic.
If the above is the case, then you two would probably agree on a lot of basic beliefs (Trinity, etc.) but there would be a lot of differences. If you’re thinking about marriage and future children, you will need to discuss issues such as birth control and what faith the children will be raised in.
Evangelical Christians generally believe abortion is a sin, but they are not as a rule against birth control when used by married couples. My understanding is that Catholic teaching is more restrictive on this, and that might not be something she is prepared to follow.
Also, my understanding is that Catholics have to baptize their children in the Catholic Church and raise them as Catholics. This would most likely be foreign to a non-denominational evangelical Christian. Most of these churches practice believers’ baptism and do not baptize infants. She may believe that a person should make their own decision to be baptized and join a church only after coming to true faith in Christ. And it might disturb her that she’s expected to automatically raise children in the Catholic faith rather than teach them her own church’s beliefs or at least expose the children to both parents’ churches.