I think that's good advice actually --- anytime someone feels strongly about something, they should marry someone who is pretty compatible with that. If you're a country person, you should think hard before marrying someone who has to live in a city, if you have to have cats, don't marry a cat hater. I know people in mixed marriages who say that religion wasn't so important during the courtship but suddenly after the kids start coming it becomes more important and the source of many problems. But it depends on how important it is to both parties. I can relate; my mom was a devout Catholic and my Dad was nothing in particular, but it didn't take too long for him to get very hostile towards her (and my) Faith. It was not a happy situation for me growing up.
There are two good examples I can think of right off the top of my head ---- one guy is a devout Catholic and his wife a semi-practicing Jew --- they were sure they could work it all out --- after all kids make their own decisions about religion eventually anyhow --- but he said everything was fine until the first child was born, the wife's religion suddenly became more important to her, his even more important to him --- and once you baptize a child, he really cannot be Jewish. Their marriage worked but he said his advice is --- don't do mixed marriages.
Another couple --- she a non-practicing Jew, he a fallen away Catholic who never goes to church. She'll put up a Christmas tree, serve ham for Christmas and throw in a few Jewish traditions now and then, they never had any problem, raised their kids with no faith --- except were kind of surprised when one son became a born again Bible thumping Protestant. They actually had to tell him because he would try to convert them that they never bothered him with religion and they'd appreciate the favor returned.