Religion, existing as a specific fundamental set of beliefs and practices generally agreed upon by a number of people or sects, is real. It is a concept that exists independently of all other things and from which all other things derive.
Religion can be used to describe the overall belief system of specific deities and purpose of behaviors; however, religion itself is merely a means of defining the actions humans take in participating together to share a belief. Which religion is correct or real is a subjective question that can only be answered by the believers in the specific sect being questioned. Each modern human religion cancels the other out in terms of "correct belief systems," but the very practice of gathering people to practice a belief is religion itself.