John Chrysostom

But Philip here by his word also won them over, discoursing concerning the kingdom of Christ. "And Simon," it says, "being baptized, continued with Philip": not for faith's sake, but in order that he might become such as he. And how came he to baptize Simon also? Just as Christ chose Judas. And "beholding the signs" which he did, forasmuch as the others did not receive the power of working signs he durst not ask for it.

But why did they not correct him instantly? They were content with his condemning himself. For this too belonged to their work of teaching. But when he had not power to resist, he plays the hypocrite, just as did the magicians, who said, "This is the finger of God." And indeed that he might not be driven away again, therefore he "continued with Philip," and did not part from him.