What does Paul mean when he calls the Galatians foolish?

In Galatians 3:1, Paul confronts the Galatians by stating, 'O foolish Galatians, who hath bewitched you, that ye should not obey the truth?' This rebuke reflects their inconsistency in understanding the gospel, as they were tempted to return to the law for justification instead of relying solely on grace. Their foolishness lies in failing to grasp the sufficiency of Christ's sacrifice and the consequence of seeking righteousness through works, which leads to spiritual deception. Paul's stern language serves as an urgent call for the believers to return to the foundational truth of the gospel that emphasizes faith in Christ alone for salvation.