That's just good manners; you bare your head to show respect, as you cross the threshold. You don't wear a hat in someone's home (or the House Of God, for that

That's just good manners; you bare your head to show respect, as you cross the threshold. You don't wear a hat in someone's home (or the House Of God, for that matter). And if you want to show respect to someone, you raise your hat (or just tip the brim, if all you're willing to do is go through the motions). I find that raising my hat tends to cause startled looks. But I still do it.