Galatians 3:8-12, especially vs. 9: "So then those who are of faith are blessed with believing Abraham." Christians in the West, influenced by Scholasticism, the Protestant Reformation, and the ensuing Counter-Reformation, divided sharply in their understanding of faith and works in salvation, even turning them into opposites. The battle cry of Protestants became "sola fidei," by faith alone. Roman Catholic teachers upheld the Church's traditional high regard for good works but over-emphasized them to minimized faith.
Then, in the West, texts from the Epistles to the Galatians and the Romans became sources for reinforcing the position of "faith alone" held by the Reformers, and the Roman Catholic Church fought back, quoting the Lord Jesus and the Epistle of James. The Orthodox Church, separated from this controversy by geography, culture, and its own theological comfort in the synergy of faith and works, continues to repudiate all opposing of faith and works.
In today's reading from Galatians, the Apostle clearly differentiates "those who are of faith" (vs. 9) from those who "are of the works of the law" (vs. 10). The passages provide a starting point for examining the Orthodox understanding of the mutuality of faith and works.
First, two givens: Orthodoxy understands that in the economy of God both law and faith are essential. Further, an Orthodox reading of today's passage assumes that the opposition which St. Paul describes involved issues that were contested and settled during the Apostolic age.
Both St. Paul and his opponents accepted Christ as Messiah and Lord. However, those who were "of the works of the law" opposed St. Paul's reception of Gentile converts, being convinced that it was necessary to 'complete' converts by requiring them to adopt the full panoply of rituals demanded by the Mosaic tradition: circumcision, keeping of the dietary laws, and the regular Jewish observance of special seasons and days of fasting and celebration.
St. Paul vehemently repudiated these demands for cultic conformity to Mosaic practice. In this rejection, he represented the common position of all the Apostles (see Acts 15). The Apostles' orientation to salvation, based on the leading of the Holy Spirit, rejected conformity to the majority of the visible rituals of Judaism, in favor of living the Way of the Lord Jesus.
Hence, in Galatians 3:8-12, the Apostle holds up Abraham as a model for all who are saved by the preaching of the Gospel. He asserts that all the Faithful are saved by living the Truth to which God calls them. As he asserts: Abraham, centuries before the Mosaic Law and before he received circumcision as a sign of God's covenant with him and his descendants, already had the Gospel concerning the conversion of the Gentiles revealed to him (vs. 
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Observe how St. Paul calls the ancient Patriarch, "believing Abraham" (vs. 9). He concluded that there was no necessity to maintain practices given centuries later. God blessed Abraham for believing Him long before his descendant, Christ Jesus, won the salvation of all by His death and Resurrection. When non-Jews, the Gentiles, believe in Christ Jesus, they become "those who are of faith" (vs. 9) and are Divinely blessed with Abraham. They are saved without the necessity to keep the many practices of the Mosaic tradition - just as Abraham was saved.
What about all the high ethical requirements of the Law? In St. Paul's view, these existed before they were codified under Moses. Men knew such requirements in their hearts (Rom. 2:14, 15). Furthermore, the Lord Jesus Himself expects all who believe in Him not to break "one of the least of these commandments" (Mt. 5:19), but, through faith in Himself, to do these works by faith. Those who have faith in Christ keep the commandments in joyful thanksgiving.
O Lord Jesus, true fulfilment of the Law, fill our hearts with joy and gladness always.