Deuteronomy - Chapter 30

Moses tells the people that it is possible for them to understand, believe and obey the covenant:

“This command I am giving you today is not too difficult for you, and it is not beyond your reach. It is not kept in heaven, so distant that you must ask, ‘Who will go up to heaven and bring it down so we can hear it and obey?’ It is not kept beyond the sea, so far away that you must ask, ‘Who will cross the sea to bring it to us so we can hear it and obey?’ No, the message is very close at hand; it is on your lips and in your heart so that you can obey it."

Paul quotes these verses in Romans 10, applying them to faith in Jesus:

For Moses writes that the law’s way of making a person right with God requires obedience to all of its commands. But faith’s way of getting right with God says, “Don’t say in your heart, ‘Who will go up to heaven?’ (to bring Christ down to earth). And don’t say, ‘Who will go down to the place of the dead?’ (to bring Christ back to life again).” In fact, it says, “The message is very close at hand; it is on your lips and in your heart.” And that message is the very message about faith that we preach: If you openly declare that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For it is by believing in your heart that you are made right with God, and it is by openly declaring your faith that you are saved."