Christ was cursed. We are blessed.
"Christ redeemed us from the curse of the Law, having become a curse for us - for it is written, "cursed is everyone who hangs on a tree" - in order that in Christ Jesus the blessing of Abraham might come." (Gal. 3:13-14a)
A curse (κατάρα), in the ancient world, was a pronouncement that brought harm to someone. In a legal context, a curse was the court's sentence as a consequence of breaking the law. The courtroom curse expressed the execution of punishment on the lawbreaker, indicating that the judgment was in effect from that moment in time. The curse Paul is talking about here is the judicial action of God whereby he sentences all who break the law at even one point to the full consequences of the law. Therefore, redemption from the curse is necessary to free us from the sentence of God. Christ redeemed us (ἐξηγόρασεν) from the curse of the law by paying the price to satisfy the law's requirements (TDNT, 1:449, 126).
Everyone who tries to earn God's favor by keeping the law is under the curse of the law because we all fail. No one is perfect (Gal. 3:10). If you live by the law, you will die by the law. We are already under the curse. Burton argues that the curse of the law refers only to the legalistically imposed curse and is not God's curse. He attempts to prove that God does not curse people, the law does, and people falsely think that God curses people in the law. The curse of the law is not the wrath of God, in his view (Burton, Galatians, 168-171). His argument hardly holds water. The law is the expression of God, so the curse of the law is the curse of God in judgment for sin. We cannot differentiate between the two in this passage.
Christ redeems us from the curse having become (γενόμενος) a curse for us. The Aorist participle should be understood as instrumental, telling us the means Christ used to redeem us. He paid the price of redemption by becoming our curse. The time of the participle is antecedent to the main verb. (D&M, Grammar, 228, 230). He became the curse of the law before He redeemed us, grounding the redeeming in the becoming. The fact that Christ became a curse for us is the means by which He redeemed us. To hang on a tree was to be cursed by God (Deut. 21:23), and to be cursed by God for even one element of the law is to be cursed for the whole law (Gal. 3:10; Deut. 27:26). (Bruce, Galatians, 164-165)
Christ became a curse for us (ὑπὲρ ἡμῶν). He came to be a curse because he was innocent in himself. He had committed no sin. He was cursed in our place. The preposition should be taken substitutionally. We must not draw a rigid distinction between the prepositions "on behalf of" (ὑπὲρ) and "instead of" (ἀντί) because often the one who acts on behalf of someone is acting in place of that person (Moule, Idiom Book, 64). The substitutional force of this passage is even more apparent when Paul writes, "He made Him who knew no sin, to be sin on our behalf" (2 Cor. 5:21). Both 2 Corinthians 5:21 and Galatians 3:13 use the same expression - "on behalf of us" (ὑπὲρ ἡμῶν).
God cursed God hanging in our place on the cross. The weight of our sin hangs on the phrase "for us." To use Martin Luther's imagery, Christ wrapped himself in our sin. Every thief, every liar, every selfish person, every adulterer, everyone who lusts, everyone who is proud, everyone who slanders, everyone who is jealous, everyone who loses their temper, everyone who is impure, everyone who worship idols, is under the curse of God. Christ became the curse for us. Christ wrapped himself in our lies, in our selfishness, in our jealousy, in our impurity, in our sexual immorality, in our lusts, in our thievery, when he hung on that cross in our place (Luther, Galatians, 163-167).
We must not unwrap our sins from Christ by trying to be good enough for God. He is cursed, so we might be blessed. The worst news becomes the best news when we accept the cursing of Christ.