From: Anglo-French religiun, Latin religion-, religio supernatural constraint, sanction, religious practice, perhaps from religare to restrain, tie back
Date: 13th century
1 b (1): the service and worship of God or the supernatural (2): commitment or devotion to religious faith or observance
2 a personal set or institutionalized system of religious attitudes, beliefs, and practices
4 a cause, principle, or system of beliefs held to with ardor and faith
Hexham's Concise Dictionary of Religion
Hundreds of different definitions of religion exist each reflecting either a scholarly or a dogmatic bias depending in the last resort on the presuppositions of the person making the definition. Religion clearly contains intellectual, ritual, social, and ethical elements, bound together by an explicit or implicit belief in the reality of an unseen world, whether this belief be expressed in supernaturalistic or idealistic terms. A number of the more common definitions are those that presume the existence of the Sacred (Peter Berger, Emile Durkheim), the Supernatural/Divine (James Frazer, Immanuel Kant, Rodney Stark), or Order/Purpose (William James).
Some definitions of the term focus more on the presence of different states of being and humankind’s grappling to come to terms with those differences, without making judgments regarding the nature of other states. George Hegel called religion "the knowledge possessed by the finite mind of its nature as absolute mind," while Friedrich Schleiermacher called it "a feeling for the infinite," and Alfred North Whitehead described it as "what the individual does with his own solitariness."
Some etymologists connect "religion" to the Latin ligare, which is the same root of the word ligament, meaning "to bind." Re-ligare, therefore, would mean to bind again, perhaps in a ritualistic manner, or in meaningful practices.
Atheist Definition: Religion is the collection of practices by which groups of people come together repeatedly to find meaning in the relationship of themselves and of humankind to all existence, known and unknown.