The basic message in Paul’ Letter to the Galatians is that we are saved by faith, and not by observance of the Law. There is a story about what prompted Paul to make that argument.
Although the religion of those Jews living in Jerusalem had always been centered on carrying out proper temple worship, the religious life of Jews in the Diaspora needed another bond to keep them Jewish. What the rabbis settled on as the proper mark of their religious fidelity was the observance of the Law.
This “observance of the Law” meant more than keeping the Ten Commandments. It meant observance of another ten thousand prescriptions that the Scribes had added to the Law over five centuries. Their Law library contained many volumes that detailed what activities violated the law against work on the Sabbath. There were as many volumes detailing what foods and spices were and were not kosher.
Jesus once said not even the doctors of the Law were able to observe all the Law’s restrictions. I don’t mean to mock those sincere people, but I have read that it was morally upright for them to find legal ways around their laws. Let me mention something I heard about Sabbath Day journeys. A religious Jew was allowed to walk no more than a thousand yards from his property. But some clever ones got around that by buying square inches of property at a thousand yard intervals all over the city. That let them walk all day without going a Sabbath Day’s Journey from their property.
Paul brings up Abraham. Abraham lived five hundred years before Moses received the law. But he was saved by faith, not the law. Genesis 15:6 says that Abraham was justified by his faith in God. If Abraham the Great was justified without observing the Mosaic Law so could any one else be so saved.