"How is it that believing in the heart brings a man into Righteousness? Why does God require belief?"
Micah 6:8
He has shown you, O mortal, what is good. And what does the LORD require of you?
To act justly and to love mercy and to walk humbly with your God.
John 6:28-29
Then they asked him, "What must we do to do the works God requires?
Jesus answered, "The work of God is this: to believe in the one he has sent."
1 John 3:21-23
Dear friends, if our hearts do not condemn us, we have confidence before God and receive from him anything we ask, because we keep his commands and do what pleases him.
And this is his command: to believe in the name of his Son, Jesus Christ, and to love one another as he commanded us.
James 1:27
Religion that God our Father accepts as pure and faultless is this: to look after orphans and widows in their distress and to keep oneself from being polluted by the world.
Hebrews 11:6
And without faith it is impossible to please God, because anyone who comes to him must believe that he exists and that he rewards those who earnestly seek him
Nice “proof-texting”, my FRiend. When you have read the entire letter for each of these and can characterize the running argument in each, let me know. Otherwise, the “verse” gimmick provided by the 14th cent. monk doesn’t actually support what you are contending.