I don't know either if Loma Linda screens, but I don't think they need to screen because the secondary itself does the job. A letter from a minister??? Aside from requesting a letter of rec. from a minister, I hear the secondary itself is difficult to complete if you are not very religious and especially if you're not 7th day adventist, given the type of questions.
They don't hind the fact that they recruit and give preference to 7th day adventists. My good friend's friend got into Loma Linda with a 23MCAT, of course he was a devote 7th Day Adventist.