What does 'faith plus nothing' mean for miracles?
Faith plus nothing means miracles come through the Spirit activated by faith, not by works of the Law. The Law could perform no miracles; the Holy Spirit worked miracles among the Galatians through the hearing of faith. Miraculous transformation and manifestations were by faith alone, with nothing added.
Les explains that the question is whether the Spirit who works miracles among you does so by the works of the Law or by the hearing of faith. The Galatians could not perform any miracles under the working of the Law; it was impossible. But when the Holy Spirit activated the hearts and minds of those pagan Galatians, it produced a miraculous transformation from paganism, idolatry, and immorality into a new lifestyle. Les says that is miracle enough in itself, and no doubt the early church had other manifestations. Paul does not explicitly delineate them, but the test remains: was it through keeping the Law or through the manifestation of the Spirit activated by faith? Plus how much? Nothing. The theme of Galatians is that we are saved by grace through faith, plus nothing, not a works religion.
He therefore that ministereth to you the Spirit, and worketh miracles among you, doeth he it by the works of the law, or by the hearing of faith?