Acts 8:11

And they gave heed to him, because that of a long time he had amazed them with his sorceries.

The influence of Simon was fortified and entrenched by years of successful operation; and his acceptance of the gospel, related a moment later, was all the more phenomenal in view of this; and with such a well established base of influence, it would appear incredible on the face of it that he would have given it up without a struggle unless his motives had been good. Certainly Elymas (Acts 13:8) opposed the gospel; and it seems mandatory to believe that Simon would have done the same thing unless he had truly believed.