To whom they all gave heed, from the least to the greatest, saying, This man is the great power of God.

People's New Testament

8:10 This man is the great power of God. Unable to explain the things that he did, the Samaritans ascribed them to divine power manifested through Simon.

Jamieson-Fausset-Brown Bible Commentary

10. To whom all gave heed . because of long time he had bewitched them-This, coupled with the rapidity with which they deserted him and attached themselves to Philip, shows the ripeness of Samaria for some religious change.

Matthew Henry's Concise Commentary

8:5-13 As far as the gospel prevails, evil spirits are dislodged, particularly unclean spirits. All inclinations to the lusts of the flesh which war against the soul are such. Distempers are here named, the most difficult to be cured by the course of nature, and most expressive of the disease of sin. Pride, ambition, and desire after grandeur have always caused abundance of mischief, both to the world and to the church. The people said of Simon, This man is the great power of God. See how ignorant and thoughtless people mistake. But how strong is the power of Divine grace, by which they were brought to Christ, who is Truth itself! The people not only gave heed to what Philip said, but were fully convinced that it was of God, and not of men, and gave up themselves to be directed thereby. Even bad men, and those whose hearts still go after covetousness, may come before God as his people come, and for a time continue with them. And many wonder at the proofs of Divine truths, who never experience their power. The gospel preached may have a common operation upon a soul, where it never produced inward holiness. All are not savingly converted who profess to believe the gospel.