"Through him and apostleship to call people from among all the Gentiles to the obedience that comes from faith."
"Obedience the comes from faith" This phrase is very interesting and is setting up the whole letter of Romans for what it is. A message that says our faith comes not of works but grace. Paul is saying in this simple line that the school teacher is not needed anymore. The law is not needed anymore. Obedience can and must come through someone's faith. They can try to follow rules and regulations all they want but it will lead to nothing but condemnation and guilt. Because that is what the law was made for. It was made to show us how guilty we are but Grace happened to show us how (despite of all sins) accepted we are.
The other day I was helping our print center at work print a banner that said "Revival Fire or Ruin" I looked at the associate I was helping and said "They would probably get more people to stop at their booth if they said 'Grace greater then all my sin' The law is very dangerous in the hands of the breakers. It will, more often then not, be used to build a fake cast system. This system is not based on truth at all but hidden lies. The people at the top of the cast system are just as bad as those they say are at the bottom but they are better at hiding it. Their motives in some way might seem good to them but the result is not freedom.
The idea of 'Obedience by Faith' says that when we accept Christ by faith and realize what He has done for us, then we are filled with a desire, passion and love for others. What were those two commandments again......? Love the Lord with all your heart, soul, mind and strength and your neighbor as yourself. By doing this you fulfill all other commandments.