No offense, but I'd need to see it from a source other than "WorthyNews"...these 'selective outrage' cases have been brought up before, and when examining the finer details, almost never hold merit.
The issue is the distinction between promotion and simply "teaching about".
I have no issues with public schools "teaching about" various major religions and their impacts on society.
However, "teaching students about a religion" and "promoting prayer in public school" are two very different things.
Praying conveys "embracing a religion" vs. simply educating people about it.
...but no public school I'm aware of is prohibiting students from praying to the god of their choosing.
Often times, I see cases where people think that "promoting Christian values" is the same as "teaching about another world religion"
I don't know of any school that forbids the teaching of historical aspects of religion like the crusades, inquisition or arab spring.