Romans 4:13-16

God does it. He justifies us. He does it freely. One of His purposes is that the promises may be sure.

The Jews have a saying that goes like this: "How can a man enter into a right relationship with God so that he, too, may inherit the promises?" They understood the promises were made to Abraham and to his seed. They wanted to be able to participate in it and so they had this question. Here was their answer: "He must do so by acquiring merit in the sight of God through doing good works, which the law prescribes." That is to say, by one's own effort.

But you see, as Paul is describing here, that destroys the promises of God because no man can keep the law! If nobody can keep the law, because the giving of the promises depends on keeping the law—if they cannot keep it, if we cannot keep it, then God cannot give the promises, and nobody would ever qualify.

So God, wanting to make sure that the promises are given, justifies a person of His own free will (God does this.) He blesses us, so that we can qualify to receive the promises on the basis of His grace. You better be glad it is that way, or we would never inherit what Abraham is going to inherit.

Romans 4:13-15

He is saying there is no way that we could be justified through law or any of that sort of thing. It does not work that way. That is not what the law is designed for. The law is designed to show us what sin is, show us what wrong conduct is, or you can flip it around more positively to say it shows us what good conduct is. But the Ten Commandments are famously in the negative. But that is its purpose. It is not to save us.