A couple of my favorite anecdotes about "mixed marriages:"
1. Though he composed beautiful religious music like "Ave Maria" and "Requiem," Giuseppe Verdi was (in)famous in Italy as a religious non-believer. So much so that many believers complained about him being paid to write the "Requiem."
Mrs. Verdi was a lifelong devout Catholic. Verdi often tweaked her about that, asking "Surely you don't STILL believe that nonsense?" And so forth. Mrs. Verdi said she often got so mad at her husband over their religious differences, she wanted to "hit him right in the head." But apparently she never did.
2. Thomas Edison was such an outspoken non-believer, he scared the corporate Board of General Electric. Especially after he gave an interview to the New York Times in which he denied the existence of the soul or an afterlife. He also said no form of religion should ever be taught in American public schools, because religion was "bunk."
His second wife, Mina, was a devout Xian. Like many another spouse, she thought her husband would eventually "come around."
Especially if, say, she invited a bunch of prestigious, well-educated clergymen to dinner. And let them introduce her husband to their awesome Other Ways Of Knowing about religion.
So after dinner, Thomas Edison and the clergymen retired to the study, where the guests all started pontificating on the absolute necessity of religious belief, etc. etc.
After a few minutes, Edison stood up and said: "I'm not listening to any more of this damned nonsense." And left the room.
After that, the Edisons agreed to disagree about religion and pretty much lived happily ever after.