Belief of a higher power. This can range from on god to millions. Monotheism means believing in only one god while Polytheistic is the belief of more than one god. The three largest being Christianity, Islam, and Hinduism.
Examples of religions that believe in more than one god are Hinduism, Buddism, and Shinto. Many religions do things to please their gods, goddesses, by having sacrifices, festivals, gifts, fasting, etc.
Religion is NOT evil. The people who taint religion are known as extremists, these people believe that they are doing whats right but kill many in the process.
So please don't be ignorant and be respectful!
Guy 1: Whats your religion?
Guy 2: Muslim, you?
Guy 1: Christian!
Guy 2: Wow! And we get along pretty well!
Guy 1: You're right!