The religious families will just have to deal with it. You are there to teach science, if they want wishing to be taught they can advocate for a wishing class. I am friends with several teachers of all different disciplines. By and large they actually have more trouble convincing parents that their precious, lazy little scut is anything but an angel. The few times that the faith of a parent or student has interfered with any of them have all ended with the parent understanding that schools have guidelines that must be met and none of those guidelines includes supporting that parent's wishful thinking. Now that may be anomolous but even my teachers from my own school days didn't bow to religious pressure, even the faithful among them. In fact I had no idea what if any faith any of my teachers held until meeting them in adulthood.