I know it was a light hearted, Lifetime movie but...
the movie shows why a lot of "interfaith" families don't work. Even if you aren't religious, you might have deal breakers...
I'm Jewish and would never have a Christmas tree, lights, go to church, not have kosher food in the house etc. Of course every Jew is different with this.
Just better to know before you give someone a ring (and imo, living with them), how you want to raise your family and where to live.
Granted some blended families work but many members often resent (even if not spoken) some members of holding back things that meant something to them.