1Paul, an apostle—not from men, nor through man, but through Jesus Christ, and God the Father, who raised him from the dead— 2and all the brothers who are with me, to the assemblies of Galatia: 3Grace to you and peace from God the Father and our Lord Jesus Christ, 4who gave himself for our sins, that he might deliver us out of this present evil age, according to the will of our God and Father— 5to whom be the glory forever and ever. Amen.
6I marvel that you are so quickly deserting him who called you in the grace of Christ to a different “good news”, 7but there isn’t another “good news.” Only there are some who trouble you and want to pervert the Good News of Christ. 8But even though we, or an angel from heaven, should preach to you any “good news” other than that which we preached to you, let him be cursed. 9As we have said before, so I now say again: if any man preaches to you any “good news” other than that which you received, let him be cursed.
10For am I now seeking the favor of men, or of God? Or am I striving to please men? For if I were still pleasing men, I wouldn’t be a servant of Christ.
11But I make known to you, brothers, concerning the Good News which was preached by me, that it is not according to man. 12For I didn’t receive it from man, nor was I taught it, but it came to me through revelation of Jesus Christ. 13For you have heard of my way of living in time past in the Jews’ religion, how that beyond measure I persecuted the assembly of God and ravaged it. 14I advanced in the Jews’ religion beyond many of my own age among my countrymen, being more exceedingly zealous for the traditions of my fathers. 15But when it was the good pleasure of God, who separated me from my mother’s womb and called me through his grace, 16to reveal his Son in me, that I might preach him among the Gentiles, I didn’t immediately confer with flesh and blood, 17nor did I go up to Jerusalem to those who were apostles before me, but I went away into Arabia. Then I returned to Damascus.
18Then after three years I went up to Jerusalem to visit Peter, and stayed with him fifteen days. 19But of the other apostles I saw no one except James, the Lord’s brother. 20Now about the things which I write to you, behold, before God, I’m not lying. 21Then I came to the regions of Syria and Cilicia. 22I was still unknown by face to the assemblies of Judea which were in Christ, 23but they only heard, “He who once persecuted us now preaches the faith that he once tried to destroy.” 24So they glorified God in me.
Paul says that those who preach anything other the "good news" he had preached should be cursed. The word for "curse" in this passage is the Greek word ἀνάθεμα (anathema), a word very familiar to the Jews, since Yahweh used it as a warning not to violate His covenant with Israel (Deut 11:36; 30:19; Josh 8:34; Psa 37:22). He promised them blessing if they followed His instruction, such as health and good crops, but if they were not obedient He would bring curse (such as disease and famine), even temporarily losing the possession of the promised land.
Paul uses this sense in Galatians 1 against those who obstructed or distorted the "Gospel." He was not condemning them to hell, but asking God to judge or condemn their actions. However, a few translations have distorted the intent of the apostle's words by translating anathema as "eternally condemn: For several years the New International Verse translated the Greek word as follows: "But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned! 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 him be eternally condemned!” (Galatians 1:8-9). Fortunately, they recently reconsidered this understanding and have changed the translation of Greek word anathema "to be under God's curse," an excellent translation of the word.
Following are a few translations with a misunderstanding of the Greek word:
"But even if we (or an angel from heaven) should preach a gospel contrary to the one we preached to you, let him be condemned to hell!" Net Bible
"But even if we or an angel from heaven should proclaim to you a gospel contrary to what we proclaimed to you, let that person be condemned!" International Standard Version
"But even if we or an angel from heaven should preach to you a gospel that is different from the one we preached to you, may he be condemned to hell!" Good News Translation