Similarly, you have stated that Christianity is a religion. You have stated it without evidence of any kind.
Although a religion requires no deity, the Global Warming religion contains the Holy Anthropomorhized Trinity of 1. the Climate goddess (the Mother), 2. Anthropogenic Warming (the Son), 3. The Holy Ghost of Greenhouse Effect.
If you really want to piss off a warmizombie, go ask him to prove that his gods exist. Ask him to SHOW you these gods that he worships. When he tells you that they really do exist and that they are all around us, but that they are just invisible and we can't see them, ask him how he knows they are real. He'll respond "Just look at nature. All the evidence points to the existence of my gods. Everybody knows they are real." Then ask him for science and you'll get this thread, i.e. a complete absence of any science support, but he'll call you "stupid" for not believing as he believes. He'll say that you should fear the consequences of not believing in the eternal damnation ... of the planet. Of course, he will demonize you and villify you as being evil for simply not worshiping as he worships.
Climate Science and Christianity, being unfalsifiable religions, both fit the definition of religion like a snug bug in a rug.