O foolish Galatians! Who has bewitched you that you should not obey the truth, before whose eyes Jesus Christ was clearly portrayed among you as crucified?
anoétos adj def lack of wisdom, stupidity arising from deadness and impotence of intellect
Foolish does not indicate a lack of intelligence. It refers to one who doesn’t use one’s powers of perception or doesn’t reason through a matter.
Here in Galatians, Paul’s expression is a mix of surprise and indignation. He follows by asking a series of questions showing the church how absurd the notion of their Christian lives being matured by self-effort instead of relying on the Holy Spirit’s leadership.