I recall as a kid and growing up attending Catholic school we were always forbidden to wear hats in church. I don’t recall the “why” other than it was disrespectful or sinful. I recall my mom and dad always telling me to take my hat off in church when we would enter, and I recall the Sisters actually getting nasty if we entered the church with a hat on. With that being said though, why are we not to wear a hat in church as a male, but females are allowed to? Is it just a respect thing or is there some other basis for it (and why can ladies wear one but not men)?
In the Christian tradition, men do not wear hats in church because St. Paul indicated that men should pray with head uncovered (1 Cor. 11:4). And while the Christian tradition of women covering their heads in church has fallen into disuse, the custom for men taking off hats in church, in any indoor setting, and in the presence of women, is still considered a social norm.