It's not uncommon for a school in a rural community to have a more homogenous study body especially when it comes to religion and so just over time an elective like that might form and stick around for a long time before you have a situation like this one. I grew up in a small rural town and it was pretty much just assumed that everybody there is a Christian, maybe a variety of denominations but Christian. Im not saying that that's a good thing or a bad thing though it was just my experience. We have clubs in our high school that centered on Christ and different denominations and we had an elective about world religions that was taught by one of the history teachers. 99.9% of the student population was Christian in my school but the clubs all had less than a dozen students in them and not everybody chose religion as an elective so most students despite being Christian didn't engage in those clubs or classes and didn't feel ostracized by not enrolling or joining. It just gave the kids options for electives and clubs that allowed them to get together to discuss the Bible, but it was all voluntary. I understand why you think theres no need for that sort of thing but just as you dont think it should be there, there are students that do, and the fair thing is to provide it but make it voluntary in my personal opinion.