truereligion

They share a common ethos, an ideal of attitude, behavior, and lifestyle that characterizes something they all share, though they don't agree how closely any one of them must adhere to that ideal to still be considered one of them.
They often dress alike, across the different cultures and nations they live within.
They have a body of writings they all admire and repeat to one another, with strange expressions that outsiders don't understand. They often feel these writings are among the most beautiful and meaningful in the world.
Many of these works are openly acknowledged to be extreme, yet those who say this often celebrate the extremism, believing it is a more true form of what they value. Some of the most extreme leading people are the most admired by even mainstream followers.
Even the writings that are considered more mainstream, not extreme, often include passages that celebrate violent or destructive and illegal actions and images. Followers will tell you they would never actually carry out such actions, but these writings remain very important to them.
Gatherings of these people often have ritualistic and ceremonial characteristics. Religious images are displayed, a lead figure exhorts the crowd to group chanting, shouting, stylized simulations of violence, and it is not infrequent that participants are injured.

They can be found in nearly every country.
As religions go, heavy metal may have more followers than Mormonism and Judaism together.