They didn't know how God makes people right with himself. They tried to get right with God in their own way. They didn't do it in God's way.
Christ has completed the law. So now everyone who believes can be right with God.
Moses explained how the law could help a person do what God requires. He said, "The one who does those things will live by them."(Leviticus 18:5)
But the way to do what God requires must begin by having faith in him. Scripture says, "Do not say in your heart, 'Who will go up into heaven?' "(Deuteronomy 30:12) That means to go up into heaven and bring Christ down.
"And do not say, 'Who will go down into the grave?' "(Deuteronomy 30:13) That means to bring Christ up from the dead.
But what does it say? "The word is near you. It's in your mouth and in your heart."(Deuteronomy 30:14) That means the word we are preaching. You must put your faith in it.
Say with your mouth, "Jesus is Lord." Believe in your heart that God raised him from the dead. Then you will be saved.
With your heart you believe and are made right with God. With your mouth you say that Jesus is Lord. And so you are saved.
Scripture says, "The one who trusts in him will never be put to shame."(Isaiah 28:16)
There is no difference between those who are Jews and those who are not. The same Lord is Lord of all. He richly blesses everyone who calls on him.
Scripture says, "Everyone who calls on the name of the Lord will be saved."(Joel 2:32)