More specifically, I think an Evangelical teacher would be more prone to try to use their position to proselytize students to add jewels to their crown in heaven when they die to go get their rewards from Jesus. Bringing souls to Jesus is their mission for personal gain in the afterlife. Making sure they have a mansion in the better part of town.
That is why I believe they are the primary voices worrying about homosexuals teaching their students, because they worry they might do what they would, which is try to influence children with the "religious agenda". They project this onto gays and call it a "gay agenda". Very, very telling indeed.
That is what this is all about, I believe. Worrying others have the same hidden ulterior motives that they secretly do. Trying to win and influence others to their beliefs. Trying to convert them out of personal self-interest. It's just pure guilt projection heaped onto others as deep suspicions of their motives.
They know deep down that they themselves are doing it, but project this onto others as their sins, rather than doing honest self-acknowledgment and repentance. That's all it is. It is sad really, if it weren't so hurtful to others. But conflicted people do cause a lot of pain for others as they try to escape self-responsibility. Ultimately though, they'll not be able to escape the truth of themselves. This is true for everyone, I believe.