Romans 3:19

Now we know that whatever the law says, it says to those who are under the law, so that every mouth may be silenced and the whole world held accountable to God.

(v19, NIV)

Now we get some insight to the law. The law is directed to those who are under the law. The law was given to the Jews and so it is focused on them. This doesn't change the fact that everyone is still under sin. We are all under sin. What's interesting is that Paul proceeds to talk about mouths being silenced. The fact of the matter is that nobody will be able to lift a legitimate argument against God. Sure, you can argue with God all you want. However, you will not have a valid point. There are even those who right now bring their arguments to God. However, even they will be silenced. You may speak now, but you will be silenced.