I've no doubt that there are members of the Satanic Temple who hate and disdain Christians or the religious in general. However, it's not a part of their publicly stated teachings or mission statement. Their first fundamental tenet is 1. One should strive to act with compassion and empathy towards all creatures in accordance with reason. Not exactly a seething manifesto of hatred.
Yes, in one breath they called themselves "the Satanists". In the next they declare they don't actually have anything to do with Satan. In another breath they declare "one should strive to act with compassion and empathy towards all" And the next the declare and label that all religions in general are "oppressive and tyrannical".
Under a braggart-ruse, they are teaching intolerance and hate; which is unacceptable on school grounds; and legally disallowed.