What makes religion “real”?

Those of us who follow the less “popular” religions of the world, often explain our beliefs to others, only to be told that our religion doesn’t seem “real”. Or perhaps, you are accustomed to hearing that your faith doesn’t seem “serious”. A running joke among non-UU individuals is that UU people really “believe in nothing”. But in this world, who is to say what constitutes a real religion or a “fake” one? By what merits do we legitimize religions, and decide which ones to take “seriously” or deem worthy of respect, when the very definition of religion is still debated? What sort of dangers would this present, and how would this reflect on Unitarian Universalist beliefs?