Well, let's agree to disagree. I don't want teachers (most of the women and some of the men in my family are or have been teachers) to have to second guess their instincts all the time and censor themselves for fear of being spied on by a ruthless, despicable, headline-hungry political activist. The student and his mother were in the wrong. If either of them had a scrap of integrity or decency they would have addressed their concerns directly to the teacher. If that hadn't worked, to the principal. Then to the school board, then if all else failed, to the courts. (Note the newspapers don't come in here anywhere).
Their only objective was the public humiliation and character assassination of a teacher who by most accounts was inspiring and effective, just because they didn't like his political opinions. They went about it in a devious, cowardly, reprehensible and irresponsible way. Because of their actions, the school board has $100,000 less to spend on education and an excellent teacher has been thoroughly distracted from his teaching.
IMO, if the student had had the courage to ask the teacher to tone down the irreligious comments the whole thing could have been resolved for free.