James 2:19

Thou believest that there is one God; thou doest well. — Better thus, Thou believest that God is One; thou doest well. He is the formal object of faith derived from knowledge, whether by sense, intuition, or demonstration; you are theologically correct, and may even declare your internal faith by external confession — well, indeed.

The devils also believe, and tremble. — They shudder in the belief which only assures them of their utter misery; literally, their hair stands on end with terror of the God they own. Assent, opinion, knowledge — all are thus shared by demons of the pit; call not your joint possession by the holier name of Faith. “I believe in God,” “I believe in one God” — such is the voice of the Christian; and this is said in the full sense “only by those who love God, and who are not only Christians in name, but in deed and in life.”