Galatians 3:5

Question 4: What accounts for the miracles you witnessed (cf. Acts 14:3; Acts 14:8-10)? God did not perform them because the Galatians did something special to earn them. He gave them freely in response to their believing the gospel.

Paul knew, of course, that miracles do not necessarily evidence that God is at work. Satan can empower people to do miracles too (2 Thessalonians 2:9; cf. Exodus 7:22; Exodus 8:7). He regarded the evidential value of miracles as secondary (e.g., Romans 15:19). Here he appealed to the fact that miracles accompanied his preaching to the Galatians whereas presumably they did not accompany the preaching of the Judaizers. He did this to remind them of the Holy Spirit’s miraculous confirmation of his gospel. These miracles may have been those the Holy Spirit continued to work among the believers even after Paul left. Note the present tense of the word translated "works" (Gr. energon). He continues to do miracles in and through believers even today not the least of which is the miracle of regeneration. However, Paul was speaking of the miracles that his original readers had witnessed.

For Paul the Mosaic Law and the Holy Spirit were as antithetical as works and faith regarding what makes people acceptable to God now (cf. 2 Corinthians 3:6).

Thus Paul reminded his readers of their own experience of salvation to prove that it was by faith alone.