Bad Teacher But Good Person Affecting Our Church Relationship

Mongoose,
One of my son's high school teachers is about as sorry of one as you'll find anywhere. The teacher is a good, moral person, but couldn't teach a dog to pee on a tire. The worst part is, we go to church with the teacher. How do I keep my personal relationship out of the classroom while also avoiding the teacher's inability to do their job out of our church relationship?

Dear Monday thru Friday and not Sunday School Teacher,
Those who can't-- teach. I read that somewhere, and I guarantee it wasn't in school. I went to high school for 7 1/2 years, I'm no dummy, and if there's one thing I learned, it was that there were good and bad teachers all over the place. Good thing for me I was able to bluff my way through most of it and finally graduate. Kindergarten, important, 1st grade, important, one year of high school, important. I'm not saying the rest doesn't matter, but I am saying once you get the three R's mastered, in my opinion, the rest is memorization. The reason I say this is after you take out fair day, snow days for heavy frosts, field trips, and selling soda pop or donuts, one year isn't going to set them back too far. I do have a solution for poor teachers though, get rid of tenure and all that union garbage and teachers get paid in tips.   Give the kids a wad of money first day of school and see which ones aren't also working part-time at the Little Dipper come graduation day. 
--MG