Personally i think the "bowing of the head" is a respect thing. Granted Christians bow their head to show respect you R13 dont have to simply bc you dont believe in him. Still you can easily conform to not make a scene by simply looking at your feet if there is a prayer or maybe about 8 feet in front of you at the ground. A lot of the instance you jus describe was brought upon yourself bc you are trying to be different and "stand up" for your beliefs. While you are standing up for your beliefs by not bowing your head, Christians are "sticking up" for their god by saying something t you. It goes both ways i think