Why must the Protestant promise that all children icill be Catholics?

You must try to see this through Catholic eyes. A non-Catholic does not, as a rule, believe that his is the only true religion, and on the principle that one religion is as good as another, his conscience does not forbid that his children should be brought up in the Catholic religion. But a Catholic is in a very different position. He believes that his is the only true religion, and does not believe that one religion is as good as another. Now how can a Catholic in conscience hand over his children to what he knows to be a wrong religion? How say, “I shall have all the benefits of the true religion, but my children won’t!” Or, “God will be worshipped by me in the way He commands, but not by my children!” Even God could not authorize a Catholic to cling to the true faith himself, yet deny that faith to his children. Without securing the promises no Catholic could conscientiously enter upon such a marriage.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty