Today, I want to share some excerpts from the beloved preacher and statesman, Billy Graham in his address on biblical authority in evangelism.  I find them current and poignant.

The great prophets of the past had also spoken with authority. The impact of their preaching cannot be traced simply to an authoritative technique. Nor was their authoritative note based on confidence merely in the rightness of their own intentions and speculations. Their secret is traceable to nothing less than the confidence that they were the mediators of Divine revelation. Throughout the Old Testament we find Isaiah, Jeremiah, Hosea, and the other prophets continually using such expressions as “The word of the Lord came unto me” or “Thus saith the Lord.” The flaming prophets of old gained their authority from this: they were not simply speaking their own words, they were mouthpieces for God.
The authority of Jesus is more than a prophetic authority. The Christian Church rightly acknowledges that in Him alone the incarnate God entered history; the very words He spoke are the words of the one and only God-man. Yet the remarkable fact is that in His teachings Jesus continually referred to passages in the Old Testament as fully authoritative. His Messianic self-consciousness, His very authority as the Son of God, are combined with the highest regard for the Old Testament as the authoritative record of the will of God.
Even a casual study of Church history will reveal that the great giants of pulpit and pen, from Augustine to Wesley, relied heavily on Scripture for their authority. in this, they followed a sacred precedent hallowed by Christ and the apostles…to be continued.