Faith accepts the testimony of God confidently, in the manner of a child, and salvation as a free gift.
The law was given to guide us to Christ; but any use of the law as a means to earn salvation is a distortion of the gospel.
By nature, humanity presumes to seek salvation through works, it seems like an offense to believe that we can not, but the word of God says that it is an offense to the Lord to believe that we can.

That is why In this chapter Paul begins the defense of his Gospel reminding the Galatians that their Christian life, which began by faith in the crucified Christ and was certified by the gift of the Holy Spirit, was completely foreign to the law, would be foolish if they abandoned the ways of God to seek perfection by their own efforts.
In this sense the Judaizers are like evil sorcerers who distract the attention of their victims by taking them from the cross to the law, however, the Galatians have no excuse because Paul has clearly explained the meaning of the cross, because, they believed that the mere fact of being descendants of Abraham justified them before God.
Paul explains to them that Abraham pleased God by faith and not by the works of the law, since it did not exist in Abraham's time.