The Greek word for "bewitched" is used only this once in the New Testament and does not necessarily refer to witchcraft as such. The connotation is "fascinated" or "deceived." Unlike most of his other epistles, the book of Galatians includes no commendations from Paul, nor even any prayer requests. Paul evidently was very disappointed in this church and its ministry.
He had clearly preached the gospel to them, setting forth "Jesus Christ, and him crucified" (1 Corinthians 2:2) among them, and they had apparently believed and started out well. They seemed to understand the great doctrines of salvation by grace and of liberty in Christ, and it was hard for Paul to understand how they had been so quickly led astray.
If anything, this is even a greater problem today than in Paul’s day. Professing Christians are being "tossed to and fro . . . with every wind of doctrine" (Ephesians 4:14)--not only with legalism (as in Galatia), but also with evolutionism, hedonism, emotionalism, materialism, and many other unscriptural heresies. Many who profess to be Christians have, like the Galatians, been "bewitched" by clever persuasion and peer pressure into such deceptions.
They may consider themselves especially enlightened in some way, or intellectual, or just up-to-date, but Paul would call them "foolish" just as he did the Galatians. In Christ alone--our Creator, Redeemer, and Lord--are "hid all the treasures of wisdom and knowledge" (Colossians 2:3). As Paul concluded his letter to the Galatians: "God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world" (Galatians 6:14). HMM