What is manifested now, and what witnesses to it, in the passage Les is explaining?

Les explains that the righteousness of God without the law is manifested—brought into the spotlight. It is witnessed by the law and the prophets. He emphasizes Pauline teaching but insists the Old Testament is just as well fitted and dovetails with the New. The Old Testament was predominantly under the economy of law for Israel, with temple worship, priesthood, and sacrifices. But now that God has turned to the Gentile, that economy had to slip off the scene, and something totally different is in view. This language is not found in the Gospels or the Old Testament because it is part of the revelation Paul speaks of—the mystery, the secrets held in the mind of God, now being revealed.