Every dictionary has a definition of religion, but not every definition is equally good. Some are decent, but others are horrible. Sometimes older dictionaries have better definitions than newer ones, but more recent comprehensive dictionaries tend to have the better overall definitions of all. It's easier to understand what religion is if you understand the advantages and disadvantages of some of the more commonly cited definitions found in dictionaries.

 

Webster’s Third New International Dictionary, 1971:

• Religion: 1. the personal commitment to and serving of God or a god with worshipful devotion, conduct in accord with divine commands esp. as found in accepted sacred writings or declared by authoritative teachers, a way of life recognized as incumbent on true believers and typically the relating of oneself to an organized body of believers,
  
  2. the state of a religious,
  
  3a. one of the systems of religious faith and worship, 3b. the body of institutionalized expressions of sacred beliefs, observances and social practices found within a given cultural context,
  
  4. the profession or practice of religious beliefs,
  
  5. archaic, scrupulous conformity,
  
  6a. a personal awareness or conviction of the existence of a supreme being or of supernatural powers or influences controlling one’s own, humanity’s, or all nature’s destiny,
  
  7a. a cause, principle, system of tenets held with ardor, devotion, conscientiousness and faith, a value held to be of supreme importance, 7b. a quality, condition, custom, or thing inspiring zealous devotion, conscientious maintenance, and cherishing.

One noteworthy aspect of this definition is #7, which refers to causes and principles which people pursue with zeal. This is often the origin of misunderstandings about religion because people fail to realize that, when the word religion is used in this sense, it is being used in a metaphorical way. Thus, baseball isn’t really a religion for some people — when used in that context, calling it a religion simply means that they follow it in a way which is more akin to the devotion normally reserved for religion.

 

The Oxford English Dictionary, 1971:

• Religion:
  
  Action or conduct indicating a belief in, reverence for, and desire to please a divine ruling power; the exercise or practice of rites or observances implying this.
  
  A particular system of faith and worship.
  
  Recognition on the part of man of some higher unseen power as having control of his destiny, and as being entitled to obedience, reverence, and worship; the general mental and moral attitude resulting from this belief, with reference to its effect upon the individual or the community; personal or general acceptance of this feeling as a standard of spiritual and practical life.
  
  Devotion to some principle; a strict fidelity or faithfulness; conscientiousness; pious affection or attachment.

The Oxford English Dictionary is one of most respected sources for how words in the English language are and have been used, so its entry on religion merits careful consideration. The first definition focuses upon belief in divine powers, which is how people in the West typically conceive of religion. The second and third, though, delve more deeply into the subject by describing psychological and sociological aspects of religious belief systems.

 

The World Book Dictionary, 1976:

• Religion:
  
  1. Belief in God or gods,
  
  2. worship of God or gods,
  
  3. a particular system of religious belief and worship,
  
  4. anything done or followed with reverence or devotion.

This is the worst of the lot — the definitions here are refer to belief in gods, a circular “system of religious belief,” and the metaphorical sense of religion. That is misleading to anyone trying to get a better grasp of what it means for a belief system to qualify as a religion.