Very difficult question to answer. I have friends who were raised in such a household. I think the person with the greater religious values of the two parents will end up passing on her/his values to the children. Alternately, the children can grow up and explore their own preferences.
Pretty tough question as this is something cultural where change is hard to accept. However, when you talk about a religion you are talking about a practice that has be culturally created. You have a number of religions with different focal points. I believe "belief" is the key. Ultimately all religions have one thing in common and that they believe in a God. Unfortunately religion now leads to discrimination where people are persecuted for their choices. In the end, it does not matter, and it is based on a decision where both of you decide is the best direction to go as a family!
As a senior citizen, I remember the times when Catholicism topped Protestantism every time. I doubt whether that is the case today. It could degenerate to listing the pros and cons. Besides which, didn't you discuss this before procreating?
Married in Catholic Church by Parish Priest, assisted by Methodist Minister.
Son, baptised Catholic, went to Anglican School, attends Uniting church.
Daughter, baptised & went to Uniting School & married by a civil celebrant.
Talk about an Eucumenical family!
There were never any 'religious wars' in our house!