The question was put:
"I know a married couple who are both Catholic. The wife has been investigating the Church for the past year and seems favorably inclined to join. The husband is very opposed to her joining the Church (he rarely lets the kids go with her to Church). If she does join the Church, is the husband justified in divorcing her for leaving the faith that they both committed to live when they got married (i.e., Catholicism)?"
To which I responded:
Marital partners quite often marry on the assumption that their spouse holds, and will always continue to hold, a certain set of beliefs. One thing I have learned is that people and their beliefs often change, and we cannot reasonably expect, especially if we marry before the age of 35, that in 10 or 20 or 30 years beliefs will necessarily be substantially the same as when we got married. In general, it is completely legitimate for marital partners to seek their own happiness by picking a marital partner on the basis of religious belief (or lack thereof), and it is even legitimate (with conditions) for couples without minor children to divorce if one partner's belief system undergoes a radical change (whether suddenly or over time). However, when children are involved, I tend to think that personal religious preferences of one's spouse are surpassed in priority by the well-being of the children, and for that reason, in general, married couples with minor children should stay together if the relationship is tolerable and each spouse has a minimum quantum of good characteristics to be a decent parent. Naturally it is a sad thing for any couple (or the children) to suffer the stress and friction which is almost certain to result from different religious beliefs. Probably the most difficult challenge is deciding how the children should be raised when spouses strongly disagree on religious issues. Again, provided that each spouse possesses enough objective good qualities to make them a good parent, compromise and tolerance seem to be the only viable option. And anyway, it is probably very unrealistic to expect that children be raised in an environment where their parents never disagree. If arguments are conducted in a civil and respectful manner, it can be very healthy for children to observe first-hand the reasoning process of adults and they will generally benefit from having exposure to different viewpoints. Of course, some arguments may be about subjects which the children lack sufficient maturity to digest and understand, in which case it is perfectly appropriate for those discussions to take place behind closed doors outside the presence of children.