The point is that you have 40+ applicants who all look the same on paper. You can remove the religious component to it and they still look the same on paper. They are smart and have good grades and often speak a foreign language, but their background, extracurricular, college, and life experiences are all very similar. A Med school wants to produce doctors from a variety of different backgrounds to serve a diverse patient population. They have church members applying from other schools who may not face the same scrutiny (showing it’s not entirely a religion issue). It’s about producing doctors who will serve all the different communities that exist.