Adam Clarke

For the kingdom of God - The religion of the Lord Jesus is not in word - in human eloquence, excellence of speech, or even in doctrines; but in power, εν δυναμει, in the mighty energy of the Holy Spirit; enlightening, quickening, converting, and sanctifying believers; and all his genuine apostles are enabled, on all necessary occasions, to demonstrate the truth of their calling by miracles; for this the original word often means.