I come from a long line of mixed marriages. As in Catholics wedding non-Catholics.
My mother was raised in a family with a Protestant mother and a Catholic father. Those were the days when the Church insisted my grandmother promise that she would raise the kids Catholic. Which she agreed to. Every Sunday she dutifully sent her seven children off to mass (Grandpa was a fireman, and he attended the mass that his shift allowed) while she enjoyed time, all by herself, reading the Sunday newspaper. My mother had nothing but praise for her mother's religious mentoring. She claims that it saved her from the guilt that so many Catholics carry. "Thank God for my Protestant mother," she would often say.
As kids, when we came home from Catechism class all wide-eyed with sordid descriptions of hell or what would happen to us if we should bite down on the Communion wafer, Mom dismissed whatever the stern instructor tried to plant in our heads, and say, "Children can't go to hell. And all mothers go to heaven, because God knows it's the hardest job on earth."
My father converted to Catholicism when he married my mother. Just between you and I, it never really "took." For a number of years he attended mass because he felt a deep spiritual connection with Father Dresen, also an avid fisherman. For a brief period of time he was a devout CAPE (Christmas-Ashes-Palms-Easter) Catholic. But for the most part, my brothers and I were raised attending Sunday mass with Mom and going to Catechism, or CCD, which she taught for a number of years.
I continued the mixed marriage tradition myself when I married Dan. He was a great sport about the whole thing, although he did make the priest blush when we went to see him to plan the wedding ceremony. Peering down his nose through his reading glasses, Father Murphy looked over his notes. "Well, now," he said, "We have two options for the vows. There's the long version and there's the short version." To which my husband-to-be replied, "Well, Father, the way I see it, it's like a girl in a bikini. You want enough to cover the subject, but brief enough to keep it interesting." My heart stopped for a moment as Father Murphy turned beet red, and then it started beating again when he let out a huge guffaw.
It will be interesting to see what happens with my own kids. They all went through Catholic grade school (which, if my mother were at the Golden Gates, would mean automatic admittance for my husband), but it was our choice for a variety of reasons. The main thing is that, as a result, they have a strong foundation in faith, and how they choose to proceed from here is up to them -- no matter what 'flavor' religion it happens to be.
I suspect my kids will surprise me. They're good at that. They'll question and try different things, like my oldest son who, at one time, decided he would start his own church. He loves an audience. And like so many people, they'll go through those dry spells where they're sure they just don't believe in anything. And that's okay. Because whenever they say to me, "But I don't believe in God," I tell them, "You don't have to. Because He believes in you."