W. Austin Gardner
Preacher's authority is the Inspired Scripture

There are those who believe one’s view of the inspiration of Scripture is unimportant and not a factor in the matter of preaching.
Andrew Blackwood in his book Preaching from the Bible says, “Fortunately a man’s effectiveness in the pulpit does not depend upon his theory of inspiration.”
I could not disagree more. I believe the preacher’s view of inspiration is crucial in the matters of both sermon preparation and pulpit effectiveness.
There is no question in my mind that the reason for a sharp decline in pleaching in this century is to be found right here.
For many years in theological circles there has been widespread rejection of the doctrine of verbal plenary inspiration of the Word of God. The critics have insisted that the Bible is subject to errancy and human limitation.
That has inevitably resulted in a sharp decline in Bible preaching. If the preacher loses his conviction that the Bible is the source of authority, why will he bother to preach from the Scriptures?
Merrill F. Unger’s statement is pertinent: “If the Bible is considered merely to contain the Word of God, rather than actually to be in toto the Word of God, there is naturally a decreased sense of responsibility to study its text minutely, or to systematize its theology, or authoritatively to declare its message.”
Jerry Vines, A Practical Guide to Sermon Preparation