What we should do is see whether the Catholic religion (and other Christian religions in general) have any definite rules in their own religion (that is, from their own religions, not leaning on laws of nation-states) explicitly saying that the mother may have visitation rights if there is a divorce. My guess would be no, since how can one make rules for something that is not accepted in one's religion (like asking Muslims to make rules on how to eat pork, a totally senseless suggestion). So in such a case the Muslim would be in a better situation, since there are at least rules on what to do when there is a divorce, while in many Christian religions there is no acceptance of a divorce, and as a consequence no rules as to what happens when it occurs.