The preacher must put himself out of the way and let God's Word speak through him unhindered. No matter what his training, experience, or personal abilities, he has spiritual authority only to the extent that what he says conforms to God's Word. But as with Jesus' own teaching, when a minister of God does faithfully proclaim that Word, those who reject his teaching reject God's truth and are as much accountable for their rejection as if the Lord had spoken the truth with His own lips. It is in that way, and only in that way, that a pastor is able to speak with spiritual authority. It is also in that way that he is commanded to speak with spiritual authority.
John MacArthur