Even though you both may be Christians, you may not agree on significant beliefs or what church you will attend.
For example, one issue we had to work through prior to getting married was our view on the place of children in the Church. I had come to believe the historic Christian position that children of believing parent had a special place in the visible body of Christ. But my husband had been raised in a traditional Baptist church that had different views.
We studied Scripture together and he came to embrace my beliefs. If we had not agreed, we would have set ourselves up for significant conflict down the road.
Within the broad umbrella of Christianity, you will find a lot of disagreement. A clarifying question to ask is this: “Can we agree on a shared belief system that we can teach our children and that is consistent with Scripture?”
Don’t be afraid to push pause on the marriage plans until you are confident you are on the same page.
If asking the person to wait while you work it out is too much for them, that may be a good indicator you were headed for bigger problems anyways.