There are many religions in our world and they are all different. Each one has a unique dogma that affords comfort to the believer and helps him cope with a chaotic and confusing world ... each one except for Global Warming that is. This religion seems only to instill fear and panic. Most religions are portrayed as a form of "good news" to be celebrated whereas everything about Global Warming is hyped as "bad news" that might already be "too late" and "past the tipping point."
Further, most religions are honest matters of faith whereas the Church of Global Warming specifically targets for recruitment the gullible and the scientifically illiterate because its dogma mandates the belief that egregious violations of physics are "Settled Science."
Question: why would any rational adult adopt the Global Warming faith?
Well, anyone who does not believe that the planet warms up and cools down over time isn't really rational. This planet has been warming and cooling for billions of years.
The real question you want to ask, is how much has mankind influenced this.
That answer is pretty complex, but the bottom line is, "Not Much".