“Therefore, my dear friends, just as you have always obeyed, so now, not only in my presence but even more in my absence, work out your own salvation with fear and trembling. For it is God who is working in you both to will and to work according to his good purpose.” Philippians 2:12-13 CSB https://bible.com/bible/1713/php.2.12-13.CSB

The tension in Christianity is between salvation by faith and grace alone because of Jesus’ work alone and the necessity to obey everything Jesus commanded. Every religion requires people to obey the god of that religion. Every believer in a god accepts they will be judged by their good works against their bad works. Yet Christianity teaches that no works a person does are sufficient to overcome their bad works. Our very nature is corrupt, making living a perfect life impossible, the very requirement a perfect God must have for people to be righteous or holy before Him. Only Jesus, Himself fully God though also fully Man, lived a perfect life and could, therefore, by His choice, exchange that life for ours both for receiving the punishment we deserve for our disobedience, He died on the cross for sins and for appropriating to us His perfection making us righteous before God, proven by His resurrection from the dead. There is nothing more for us to do, having come to believe that Jesus did everything that needed to be done. Yet, we are encouraged to obey God. We must obey God, for our obedience proves we believe God has reconciled us to Himself through His Son. Now that we, too, are children of God, we are to live as the Son of God who lived in perfect obedience to Father God. We must choose by our will and then depend upon His Spirit, Who lives in those who believe in Jesus, to empower us to obey Jesus. Still, this war between our will and God’s will manifests even in the Christian life. God does not transform us into robots but changes us incrementally into His image as we participate with Him in this work by obeying His commands. The final change will occur when we pass from this life to the next and receive the body that no longer seeks to rebel against God and insist upon its own way against man. This is given to all those but only those who love God by believing in Jesus alone for reconciliation with God.