“Then those who feared Yahweh spoke to one another, and Yahweh gave heed and heard it, and a book of remembrance was written before Him for those who fear Yahweh and who think upon His name. “And they will be Mine,” says Yahweh of hosts, “on the day that I prepare My own treasured possession, and I will spare them as a man spares his own son who serves him.” So you will return and see the distinction between the righteous and the wicked, between one who serves God and one who does not serve Him.” Malachi 3:16-18 LSB https://bible.com/bible/3345/mal.3.16-18.LSB
As Christians, what we do matters, and it matters quite a lot. The gospel or good news from God to man through Jesus the Savior is that man can only be saved by His works appropriated to men who believe in Him as that Savior. The disobedience of all men must be punished. It cannot be erased by doing good. Jesus died on the cross, condemned by God the Father and punished for the sins of all those who look to Him for pardon and mercy. The perfect life Jesus lived is exchanged for the Christian’s disobedient life. Jesus was punished, and the Christian is declared righteous before God and so can live forever with God and the Lord Jesus, Who is the Judge of all men for determining whether they enter heaven or hell because they came to Him for their salvation. Those who tried on their own to earn God’s favor through their good works will be condemned. Those who come to Him in humility, confessing the failure of their good works but believing that Jesus’ good works have been appropriated to them at the cross will be received by Jesus to live forever with Him. Those who are genuinely Christians do good works to glorify God on earth so that men can experience the goodness of God. God then rewards these works as an eternal treasure to Christians who live with God for all eternity. The good works God rewards are those works that serve His eternal interest, which is the establishment of His kingdom upon the earth as it is in heaven. We call this work evangelism and discipleship, obedience to the Great Commission. God records this work to reward His people who lived like His Son as a servant to His will.