Because climate activism is based on a trust in scientific consensus, the claim that climate activists are religious fanatics is a particularly effective way to delegitimize their cause. Yet ultimately those who deploy this strategy struggle to put together a credible case for why climate change shouldn’t inspire a fanatical, even religious, passion for justice.
It's a self own when reactionaries use this argument because it implies they are soulless "not religious" people who have no transcendent devotion to the sublime or anything.
Even atheist humanists can be religious, but capitalists have no subjective experience in their empty lives, nothing but "devotion" to being a consumer in the marketplace.