If you are a person of faith seeking admission to grad school, more power to you! But be sure that the persons whom you ask to write letters of recommendation for you exercise caution.
I once received a note from an acquaintance at a highly ranked religious university, who was flabbergasted that the student he had recommended for graduate studies – probably the best he had ever taught -- hadn’t been admitted. He wondered whether I might have any idea why he wasn’t.
The young man was intelligent, strongly motivated, and had good character. He had done excellent undergraduate papers, and both his grade point average and his GRE scores were stellar. His personal statement was very good, and all of his recommenders praised him to the skies. By every conceivable measure, he was superior.
One of the applicant’s professors had naïvely devoted a few sentences of his letter of recommendation to what a wonderful Christian the young man was.
Apparently the writer didn’t know that at many secular universities (and even at some nominally religious ones), that is the kiss of death. He might as well have remarked that the student wore a codpiece, spoke only in Klingon, or was an expert in the application of thumbscrews.
Perhaps that wasn’t the reason for the student's rejection. But the chances are good that it was.
So if you are applying to a secular graduate school, and if any of your recommenders are persons of faith, make sure they know that the members of admissions committees probably aren’t.
It’s fine for your letter writers to describe your intellectual strengths and weaknesses. Are you intelligent, imaginative, and logically rigorous? Do you possess initiative? Are you willing to follow evidence wherever it may lead? Are you collegial, and open to hearing new points of view, whether in class or conversation? Do you take constructive criticism in good spirit? When you disagree with others, do you speak with respect? Do you have good reasons for wanting to enter grad school? Is your interest in teaching and research strong, serious, and persistent? All that is grist for the mill.
But these souls should be as silent about your religious beliefs as though they were proposing you for a quiet civil service job under Nero or Domitian.
Don’t explain this to your recommenders yourself. You don’t want to be the sort of person who tries to teach his teachers. But it wouldn’t be presumptuous to share this post with them.
Maybe they don't need it. But they might.