And having been set free from sin, you became slaves of righteousness. Romans 6:18
Before you were a Christian you were a slave, in bondage to sin. Even when you did not want to sin, you were unable to do otherwise (Rom. 7:15-24). When God saved you, He freed you from sin, but you remained a slave. Now, rather than being bound to sin, you are bound to righteousness. In every area of your life you are obligated to do what honors God.
There are some who believe that when Christ sets them free, they are free to do whatever they want. That is not so. The apostle Paul realized that when he began following Christ he became a “bondservant” of Christ, and his life was no longer his own (Rom. 1:1). Now, rather than being enslaved to sin, he was enslaved to God and His righteousness. When people mistreated him, he had forfeited the right to respond from his natural feelings but was compelled to offer a righteous response. When he was tempted, he was no longer free to succumb to his feelings. Paul could not enter the workplace and act selfishly. He understood that, as a slave of righteousness, he was obligated to live a holy life, honoring his Master.
Righteous living is not an option for a Christian. Nor is it something we must try to do over time. It is an obligation, mandatory for every child of God. Our freedom in Christ is not freedom to do what we want. It is freedom to live righteously, something we could not do when we were in bondage to sin. Now that we are free to live righteously, we must allow the Holy Spirit to produce in us a holy, sanctified life (1 John 3:7).