How are religious ideas used in the conversation between Dr Seward and Renfield?

The religious ideas mix the occult, gothic and Christian references,

"It looks like religious mania, and he will soon think that he himself is God. These infinitesimal distinctions between man and man are too paltry for an Omnipotent Being. How these madmen give themselves away! The real God taketh heed lest a sparrow fall; but the God created from human vanity sees no difference between an eagle and a sparrow. Oh, if men only knew!" (Chapter 8)