The Holy Spirit is seen by many as a source of extra-biblical revelation to those who are “sensitive to the Spirit’s leading.” The spiritually mature, those who are “spirit-filled,” may receive a “word from the Lord,” a “word of knowledge,” or just some added insight that can’t be had simply by reading the Bible. But the Spirit does not work that way. He uses a tool given for this purpose: the sword of the Spirit. Thomas Chalmers wrote:

   The Holy Spirit’s office, as defined by the Bible itself, is not to make known to us any truths which are not contained in the Bible; but to make clear to our understandings the truths which are contained in it. He opens our understandings to understand the Scriptures. The Word of God is called the sword of the Spirit. It is the instrument by which the Spirit worketh. He does not tell us any thing that is out of the record; but all that is within it he sends home, with clearness and effect, upon the mind . . .

—Thomas Chalmers, quoted in Iain Murray, A Scottish Christian Heritage (Banner of Truth, 2006), 101.