I was in high school a zillion years ago, and for one of my 11th grade English classes took "Bible as Literature." I have no idea whether the teacher was a Christian. He did his job, and taught it as, you know, literature. Those of us in the class who were Christians were okay with that. We wouldn't have wanted to be proselytized in a public school. 
I was in a public school from the time We moved out here in '74.
Every morning there was a prayer and the Pledge of Allegiance. Same at every school assembly or event. The ten commandments were on every classroom wall. Religous discussions were a part of civics as the root of our laws.
But then, the same still holds out here in later life... Other than the ten commandments have been ripped out from in front of the courthouse, and the church bells have been silenced.
But every rodeo, stock car race, or football game still has a prayer
And I see nothing wrong at all with it. I think the 10 commandments should be back in front of that courthouse.
I think children should be taught religion according to the populace of the county.
There would be nothing at all infringing upon liberty to have the opening class every day taught by the various churches - Smaller ones might have to band together, and study hall available for those without a big enough footprint to be represented, and for those who don't want their kids to participate.
I would wager the study hall would be nearly empty. At least out here.