What is religion for them?

In short, religion is a "set of beliefs" or "something one believes in and follows devotedly". It usually has something to do with the origin of the universe and the purpose of life, and it usually points to a god or gods of some sort - Like in the case of Christianity, Islam, and other similar religions. But it also includes another type, like Secular Humanism, and Evolution, and other religions where one believes that himself is the purpose of life, or that there is no personal god. Even Atheism can be a type of religion because Atheists "firmly believe" that there is no god. It all comes down to what a particular person believes, and that determines what religion is for them. See the following definition from Dictionary.com: /rɪˈlɪdʒən/ Show Spelled Pronunciation [ri-lij-uhn] Show IPA --noun 1. a set of beliefs concerning the cause, nature, and purpose of the universe, esp. when considered as the creation of a superhuman agency or agencies, usually involving devotional and ritual observances, and often containing a moral code governing the conduct of human affairs. 2. a specific fundamental set of beliefs and practices generally agreed upon by a number of persons or sects: the Christian religion; the Buddhist religion. 3. the body of persons adhering to a particular set of beliefs and practices: a world council of religions. 4. the life or state of a monk, nun, etc.: to enter religion. 5. the practice of religious beliefs; ritual observance of faith. 6. something one believes in and follows devotedly; a point or matter of ethics or conscience: to make a religion of fighting prejudice.