Testing the Definition
It is necessary to establish that the above definition is both robust enough to include that which is generally considered to be religion while concise enough to exclude that which is not. It is also necessary to confirm, within a reasonable level of certainty, that there is a third category which does not fit into either division created by above definition.
While having a conversation one day, someone bought up a good point: religion is generally considered to require the belief in the existence of the supernatural. So why create a definition broad enough to include the belief in the absence of the supernatural? In part, this boils down to Hitchen’s razor: “that which can be asserted without evidence can be dismissed without evidence.” In this way, it is just as inappropriate to assert that there isn’t something supernatural as there is to assert that there is something supernatural and it is just as appropriate to be able to dismiss both, without giving either a second thought.
It also is not unreasonable to assume that those who are willing to make an assertion about the truth value of something for which there is no evidence and for which no investigation can provide evidence have similar thought processes, regardless of the assertion. This can be tested through various means, including surveys.
Christianity, Judaism, and Islam are more or less agreed upon to be considered groups of religions. At their core, these religions center on a belief of a god. Such a belief is religious based upon the above definition and so the definition is in line with the Abrahamic religions.
Certain sets of eastern philosophies such as Buddhism and Confucianism, and Taoism are a little more difficult to classify by standard conventions. There is often debate whether or not to classify these philosophies as religious or not. However, much of the distinction rests in why a pattern of behavior is being utilized. If the pattern is based on a belief in an afterlife, life force, deity, or similar phenomenon, then it is common to consider that form of the philosophy religious. If however a person is simply utilizing certain principles in their daily life because they seem to think it is a wise idea, such as following the noble eightfold path, perhaps because they feel such practices will provide a healthier and more fulfilling life, then it is not considered religious. This too fits in line with the definition of religion presented in this paper.
A final case study would be that of agnosticism. Agnostics assert that certain claims, especially those concerning the existence or nonexistence of a deity are unknown or unknowable. Agnosticism is considered to be a philosophy rather than a religion. Again, this fits in line with the definition of religion presented in this paper.