First of all, this article presents sociological definitions of religion and then it generally evaluates all these attempts which have tried to define religion. Many sociologist of religion have produced various definitions of religion. However, they have failed to reach a standard definition for it. Because all this definitions have been determined by their various methodological approaches. In my opinion, this is a very natural outcome, since the sociology is very dynamic and complex. This complexity and dynamism do not give a chance to a sociologist of religion to make a universal and standard definition for religion