There are many verses in Scripture that puzzle me to this day - and may continue to do so throughout my life. One such verse is found is Romans 3: "God is One - who will justify the circumcised by faith and the uncircumcised through faith." (emphasis added).
This morning, I once again came upon this verse, but after reading it probably hundreds of times, clarity came. What is the difference between BY faith and THROUGH faith? The answer is... WORKS.
The circumcised Jews already upheld God's laws and precepts. However, they lacked faith in Messiah. So, their works without faith was dead to God. On the other hand, the uncircumcised may have faith, but lack external proof that such a faith exists... "faith without works is dead" (James 2).
Therefore, the circumcised, BY showing their works (that were already being performed) combined with faith are now alive to God; likewise, the Gentiles, when they show their good works THROUGH their faith. Good works were evident before faith for the Jews and BY faith those works were recognized as righteous. For the non-Jew, although faith came first, good works were to follow as a result of - or THROUGH - their faith.
Numerous times throughout the Bible, Jesus confronted the religious leaders concerning their hypocrisy of instructing the people in righteousness, but not living out their own teaching. One's righteousness is evident through his or her words only backed by the works that follow. Why else would Messiah state, "For no good tree bears bad fruit, nor again does a bad tree bear good fruit, for each tree is known by its own fruit." (Luke 6)
Still having problems understanding the Bible? You're not alone. My simple advice... just keep reading. The Holy Spirit will bring clarity when the time is right. ;-)