And they were astonished at his doctrine: for his word was with power.
και εξεπλησσοντο επι τη διδαχη αυτου οτι εν εξουσια ην ο λογος αυτου.
Would you like to preach with power, the way Christ did? Many people have unbiblical ideas about what this would involve. The word "power" in this text is the Greek word exousia, which means "power" in the sense of "authority." In other words, Luke 4:32 teaches the same truth as 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.
και εγενετο οτε συνετελεσεν ο ιησους τους λογους τουτους εξεπλησσοντο οι οχλοι επι τη διδαχη αυτου: ην γαρ διδασκων αυτους ως εξουσιαν εχων και ουχ ως οι γραμματεις.
Christ preached with power because He authoritatively proclaimed the Word of God as Jehovah's great Prophet to His people (Deuteronomy 18:15-18). If you want to preach with power, the way Christ did, then you should do the following:
1.) As a regenerate saint, strive after greater holiness by the grace of the Father through the Son by the Spirit, that you might be like Christ in all things.
2.) Take great pains to very carefully study the Word of God.
3.) Properly and with laborious study exegete the Word properly, trusting in the illumination of the Holy Spirit.
4.) Boldly and authoritatively apply that Word after you carefully unpack and exegete it to the minds and hearts of your congregation (or the lost, if you are preaching on the street, etc.)
We can see that a godly pastor who practices expository preaching, going verse-by-verse through Scripture and carefully applying it, should rejoice that he is able to preach with power--Divine authority--in this manner, and can expect the blessing of the Trinity on his preaching. Hallelujah!
We can also see from Luke 4:32 and Matthew 7:28-29 that someone who thinks he is preaching with power because, while ripping a verse or two of God's holy Word out of context, he yells a lot, gives a lot of tear-jerking illustrations, walks around during his message, and gets many people to walk forward and kneel at the front of a church auditorium by manipulating them at an invitation is not preaching with power.
If you have thought that doing the latter was preaching with power rather than the former, you should repent now, because otherwise it will not be very good for you at the judgment seat of Christ when you find out that what you thought was power was actually wood, hay, and stubble.
If you have been preaching with power the way Christ did, be encouraged to continue very carefully expositing and applying the Word, and grow in your practice of these spiritual disciplines, that you might preach with greater power or authority the holy Word to the glory of the holy Trinity.
As an addendum, the Spirit illuminated the truth in this post to me while reading my Greek Textus Receptus. Consider taking the time to learn Greek well, that you might preach with more power.
As one more addendum, you can hear great preaching with great Christ-like power by listening to the expository preaching at Bethel Baptist Church here.