It is their heritage; their birthright. They are by no means upset at being raised in their particular faith. Rather, They are pleased to belong to whatever religion they are brought up in. Whatever they are taught by their particular sacred scriptures and/or traditions they love to openly share with others.
Children will already believe a slew of strange things at a very young age to explain all of the things they don't know about the world yet. I think it better for them to practice something a little more grounded in reality that still leaves room for wonder. There are many things that can't be explained to them that religion can help them find meaning in.
I challenge anyone who might think the religion has no use, To consider at least the fact that it can alleviate people from getting wrapped around the axel about things they cannot control in life. The hallmark of an atheist is their ability to go through life without an answer to it all. Some people (and children especially) usually need an answer to something like this so they don't overly think about it to the point of harming their ability to function in other areas.
Religion has quite uniquely given people comfort in life given the reality of our existence and how very short it is. Too short to ever know it all.
Parents shouldn't push their beliefs onto their children, Because children aren't property. Instead parents should provide guidance and expose them to different people with different beliefs and cultural values in order for them to learn what's best. I consider myself a pantheist, While my father is Catholic, My mother is a deist, And my stepfather a Spiritist, We all try our best to be open and not impose our views on others.
Children when they practice religion often do not even understand nor care about it. They just do it because their parents say so. In my opinion parents spreading their religion to children is indoctrination. Children should be allowed to explore themselves and ideas while they are young and choose what they believe in. Not what their parents believe in.