I find that calling a child catholic,or muslim, or hindu, etc, is completely unethical and unfair to the child's development. It inhibits personal advancement and thoughtfulness because its a limitation that is imposed on them--a metaphorical ball and chain. Christopher Hitchens and Richard Dawkins have argued, which I agree with, that you wouldn't call a child a republican, or a democrat, or any other political position because a child isn't old enough to understand the complex issues behind various stance--there is nothing more complicated than the nature of reality, which makes religious labeling even more disgusting.
The reasons why religions like this is obvious--its a form of early prostelization that sticks with a child more easily because their families and communities which they grew up with are peer pressuring them to conform to their societal standards. Children are also more susceptible to suggestions. However, it completely demolishes the chance for most children to have an unpolluted period of personal progress where they can individually learn about what beliefs they find most appealing. Religious families inherently tarnish this fundamentally important process.
In an ideal world I would like there to be laws prohibiting the prostelization until they are capable of making more sophisticated judgments. In conclusion parents are doing a disservice to their children by demanding that they stick to the family household religion . It really is a form of child abuse since it obliterates the potential for a child to learn for themselves, instead of being force fed a bunch of garbage created by iron age peasants.