The Jews had exorcists amongst them, who sometimes cast out devils by some forms of invocation they had; but Christ commanded them out; he neither did it by any kind of entreaty from any compact with the devil, nor yet by any invocation of God, but by an authoritative command.
This was new to the Jews, and especially confirming a new doctrine that he had published. But still we read of no believing, no agnation of him as God, or the Son of God, or the Messiah and Saviour of the world; only the generality are amazed they could not obtain of themselves to believe this new doctrine, nor yet so far command their passions, but they must be startled and amazed at it.
The fame of his miracles, rather than of his doctrine; by this means many were brought to him to be cured, many were brought also to hear him, some of whom believed, others were hardened.
[Excerpts from Matthew Poole's Commentary on Mark 1]