'Mysteries' in the Bible

Let a man so account of us, as of ministers of Christ, and stewards of the mysteries of God.

And if I have the gift of prophecy, and know all mysteries and all knowledge; and if I have all faith, so as to remove mountains, but have not love, I am nothing.

For he that speaketh in a tongue speaketh not unto men, but unto God; for no man understandeth; but in the spirit he speaketh mysteries.