Matthew 7:28-29  “And it came to pass, when Jesus had ended these sayings, the people were astonished at his doctrine:
For he taught them as one having authority, and not as the scribes.”  
Generally, our old nature rebels against “authoritarian” preachers and teachers.  However, every true teacher of the Word of God teaches with great authority.  Our authority is not of ourselves, but of the Word of God.  When we teach what the Bible says, we can do it with great confidence, great authority, and a generous amount of dogmatism.  Our hearers will be astonished at our teaching if we will just stick to the Bible as our source and our authority.