What is true of the ordinary believer respecting his confidence that his Bible is the Word of God comes in a heightened way to the preacher in the act of preaching by the ministry of the Holy Spirit. If you are a preacher, surely you have felt as I have many times while preaching the Word of God that you stood forty feet tall with a sword ten feet long and six inches wide. You felt that you could take on anyone and anything with that ‘sword of the Spirit.’ Now this sense of the absolute authority of the Word of God is not a qualitatively different different conviction concerning the Scriptures–a difference in kind from that with which you entered the pulpit. Rather, it is a heightened persuasion that, in turn, gives a note of unanswerable authority to your preaching. Since our preaching deals with God’s revealed truth, should we not expect the “Spirit of truth” to be unusually active and present as we preach, attesting to our own hearts with power that His Word is indeed truth?
from Preaching in the Holy Spirit by Albert N. Martin, p. 36