Every denomination relies on cash flows to keep afloat. Professional Protestants know that their groups will pick up increases from some lapsed Catholics. Often, Catholics find themselves in relationships that The Church deems illicit. If they value those relationships more than their faith, they will often join a Protestant denomination.
At the same time, a few will leave other religions and denominations to become Catholics. This is not a huge number of their total populations, but they are those who take God and His Scripture most seriously.
The result is that the Catholic Church is getting those who love God more than other concerns and the outlying groups are getting a larger number of those who put earthly concerns ahead of spiritual.
One ongoing attraction of the Catholic Church is in the very being of its priests. Most people in other religions are dumfounded as they explore the vows of celibacy, poverty, and obedience that Catholic priests take. They see little of those things in other groups.
The Protestant clergy, mostly married, and struggling to support their own families, may, except in big, popular churches, not be far from poverty. They are, however, far from celibacy. And, it is hard to have a great deal of obedience to denominational creeds that, themselves, stem from disobedience to earlier Catholic teaching.
