Paul here explains how faith unifies not only man with God, but the Gentile nations with the Jewish nation. Romans 4:9-25

9 Is this blessing then only for the circumcised, or also for the uncircumcised? We say that faith was counted to Abraham as righteousness. 10 How then was it counted to him? Was it before or after he had been circumcised? It was not after, but before he was circumcised. 11 He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised, so that righteousness would be counted to them as well, 12 and to make him the father of the circumcised who are not merely circumcised but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised.13 For the promise to Abraham and his offspring that he would be heir of the world did not come through the law but through the righteousness of faith. 14 For if it is the adherents of the law who are to be the heirs, faith is null and the promise is void. 15 For the law brings wrath, but where there is no law there is no transgression.
16 That is why it depends on faith, in order that the promise may rest on grace and be guaranteed to all his offspring—not only to the adherent of the law but also to the one who shares the faith of Abraham, who is the father of us all, 17 as it is written, “I have made you the father of many nations”—in the presence of the God in whom he believed, who gives life to the dead and calls into existence the things that do not exist. 18 In hope he believed against hope, that he should become the father of many nations, as he had been told, “So shall your offspring be.” 19 He did not weaken in faith when he considered his own body, which was as good as dead (since he was about a hundred years old), or when he considered the barrenness of Sarah’s womb. 20 No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, 21 fully convinced that God was able to do what he had promised. 22 That is why his faith was “counted to him as righteousness.” 23 But the words “it was counted to him” were not written for his sake alone, 24 but for ours also. It will be counted to us who believe in him who raised from the dead Jesus our Lord, 25 who was delivered up for our trespasses and raised for our justification.

There is a fundamental truth here that we must believe and apply to our lives.  Justification is through faith.  Thats it, there is nothing else to add for us to be justified.  Paul makes this abundantly clear, especially for the Jews, when he mentions that Abraham was justified by faith before he was circumcised.  This is crucial because it is easy for works to creep into our conception of justification.  For instance, believers are called to be baptized.  However, we must remain clear that we are justified by faith prior to baptism.  Baptism is a sign of obedience that a true believer will exhibit, nevertheless, it has nothing to do with justification.  Also, in reading the book of James it is easy to misinterpret and believe that works are actually part of our justification.  This is why Martin Luther thought James shouldn’t be in our Bibles.  However, this book builds the case that true faith will exhibit true good works.  It is not necessary to say that James teaches justification by works and faith.

Another truth which is foundational to the church here is that Abraham is the ancestor of the Gentiles as well as the Jews.  This surely would have been an angering fact to consider for many Jews, but remember that Paul is building a case for unity between Jewish and Gentile Christians.  Abraham is the father of the Gentiles who are justified by faith because Abraham was justified by faith prior to circumcision.  Thus, the nationalistic and prideful claim “We have Abraham as our father,” no longer carried any weight for a Jew who truly considered the means of justification.

Additionally, Paul adds to this argument by saying that Abraham remains the ancestor of the Jews as he obeyed God and marked himself with the sign of the covenant.  It is clear that obedience to the sign of the covenant - circumcision - comes after faith and after justification.  This is also instructive to the Jews who thought justification came through the law.  Paul has news for them, the law can only bring death to the one attempting to be justified by it.  Thus, this truth should be truly unifying to the Jewish and Gentile Christians.  Why?  Because they are both justified in the same manner to the same Father just as was their common ancestor, Abraham.

Paul wraps up his argument here with a beautiful and specific example of faith.  “No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, 21 fully convinced that God was able to do what he had promised. 22 That is why his faith was “counted to him as righteousness.” 23 But the words “it was counted to him” were not written for his sake alone, 24 but for ours also. It will be counted to us who believe in him who raised from the dead Jesus our Lord, 25 who was delivered up for our trespasses and raised for our justification.”  This leads me to the application.  Are we “fully convinced that God” is able to do what is promised?  He has promised that Jesus was “delivered up for our trespasses and raised for our justification.”  The question is, “Do we believe it?”  His death paid the penalty for our sin, and His resurrection completed our justification.  This is interesting that resurrection is included in the idea of justification because we usually think of the death of Christ as justifying us.  However, the truth is that we need all of Christ’s work for our justification; we need the perfect life, the death, and the resurrection.  It is not only that we need our sins washed away, but we need a righteousness then given to us so that upon our resurrection we can be with God.  Do we believe this?  Not sure?  Ask yourself what you are clinging to as your hope when you pass from this current world.  Are you still hoping in your goodness or obedience, or have you thrown all your hopes upon Christ by faith?  This is the only hope we have, the perfect work of Jesus Christ.  Only when we give up completely on our own works and trust the work of Christ will we begin to live the kind of obedience that pleases God.  Obedience in faith pleases God not because we are good when we do it, but because we are trusting Him completely when we do it, not our actions.  This is why God was pleased with Abraham, because even in circumcision Abraham trusted the God who called him to circumcision, not in the circumcision.  Let us trust God completely to justify us completely through the complete work of the only completely righteous one, Jesus Christ.