Gal 1:1 Paul, an apostle—sent not from men nor by a man, but by Jesus Christ and God the Father, who raised him from the dead— 2 and all the brothers and sisters with me, To the churches in Galatia:
3 Grace and peace to you from God our Father and the Lord Jesus Christ, 4 who gave himself for our sins to rescue us from the present evil age, according to the will of our God and Father, 5 to whom be glory for ever and ever. Amen.
To whom is Paul writing? Believers. IT's very clear. What's his warning?
verse 8 But even if we (i.e., we believers) or an angel from heaven should preach a gospel other than the one we preached to you, let them be under God’s curse! 9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let them be under God’s curse!
3:10 For all who rely on the works of the law are under a curse, as it is written: “Cursed is everyone who does not continue to do everything written in the Book of the Law.” 11 Clearly no one who relies on the law is justified before God, because "the just by faith shall live"
5:1 It is for freedom that Christ has set us free (free from under "the cruse of the law"). Stand firm, then, and do not let yourselves be burdened again by a yoke of bondage.
2 Mark my words! I, Paul, tell you that if you let yourselves be circumcised (as a means of savlation - see Acts 15:1,5), Christ will be of no value to you at all. 3 Again I declare to every man who lets himself be circumcised that he is obligated to obey the whole law.
4 You (believers in the Gatain church) who are trying to be justified by the law have been alienated from Christ; you have fallen away from grace