Rom. 4:4-5 When people work, their wages are not a gift. Workers earn what they receive. But people are declared righteous because of their faith, not because of their work.
The Apostle Paul is making it clear here that we cannot work our way into God's favor. Salvation is a gift from God and to see it any other way will prevent us from being saved. We are made right with God by receiving what He has done for us at Calvary. Jesus did all the work needed for our salvation. He took upon himself all of our condemnation for sin. He satisfied the law's demand of death for he who would sin against God. He alone was able to do it because He alone was able to live a sinless life on earth. He did all that there was to do for us to be forgiven by God and accepted by Him into His family.
We do not, nor can we ever, earn our way into heaven. We live in Christ to work, but we don't work to live. What we do proves that what Christ has done in us is for real. We live in Christ and live for Christ. All of our living should be a reflection of our salvation. We work out our salvation, but never for it. No one is made righteous because of what they do.
It is also true that no one who is truly saved will fail to show it in how they live. Works always follow salvation. We cannot live in Christ without living for Him. As long as we are able to move, we show the righteousness of Christ in us. We serve Him in all we do. We cannot be saved and do nothing for Him. He gives everyone of His children tasks to do. He equips us to do our tasks and sends us out into the world to do them. If we fail to live for Christ, we are disobeying Him and it is sin.