But if we are sons, then we are also heirs: certainly heirs of God, but also co-heirs with Christ, yet in such a way that, if we suffer with him, we shall also be glorified with him.
For as many as are of the works of the law are under a curse. For it has been written: "Cursed is everyone who does not continue in all the things that have been written in the book of the Law, so as to do them."
The promises were made to Abraham and to his offspring. He did not say, "and to descendents," as if to many, but instead, as if to one, he said, "and to your offspring," who is Christ.