1 Corinthians 12:3 - Wesley's Explanatory Notes

Therefore — Since the heathen idols cannot speak themselves, much less give spiritual gifts to others, these must necessarily be among Christians only. As no one speaking by the Spirit of God calleth Jesus accursed — That is, as none who does this, (which all the Jews and heathens did,) speaketh by the Spirit of God — Is actuated by that Spirit, so as to speak with tongues, heal diseases, or cast out devils. So no one can say, Jesus is the Lord — None can receive him as such; for, in the scripture language, to say, or to believe, implies an experimental assurance. But by the Holy Ghost — The sum is, None have the Holy Spirit but Christians: all Christians have this Spirit.