If you asked most Christians, they would very likely believe that they are supposed to keep the 10 commandments. Or, that God still judges believers based on their ability to maintain their right relationship with Him through keeping the requirements of the law.
This ideaology (which is prevalent among Christians) reveals a lack of understanding what Scripture teaches us about God's plan of redemption. The entire Bible, from Genesis to Revelation reveals God's call for people to trust Him, place their faith in Him, and then follow Him through His provision (Christ). In this calling, God reveals that no one can keep or attain to His standards of holiness. Therefore, in His great mercy, His heart is inclined to those who recognize the futility of trying to earn His favor or offering their own "law-keeping" as a means of justification. If you are a Christian, how are you saved? By keeping the law, or receiving the grace of God in Christ through faith? (Eph 2:8-9)
Jesus condemned the attitude of the Pharisees of his day for thininkg so arrogantly that they were "law keepers" to the point of self-righteousness. Believe it or not, there are plenty of modern day "Pharisees" who still take the arrogant position of attempting to earn their salvation or maintaining their salvation through works of self-righteousness. The Bible says that there is none righteous in their own standing and that all are sinners and fall short of the glory of God. (Romans 3:10; 3:23) Anytime the Bible speaks of righteousness as a human quality, it is a righteousness that has be impuned (accounted) to them by grace. (Grace: the love of God to give us what we cannot give ourselves.)
The entire Old and New Testaments proclaim the fulfillment of the law through the person and work of Christ. (That was God's plan from the beginning.) Grace is personified in that what we could not attain through the law, Christ fulfilled every requirement of righteousness on our behalf. Do you want to be judged by the law or grace? By the law you are guilty and dead, by the grace of Christ's offer of relationship, you are set free from law-keeping, and free to be obedient to your new Master through the power of the Spirit.
We are saved by grace, not by the law. We are sanctified by grace, not by the law. We are justified by grace, not by the law. So why do so many Believers think that we are still under the jurisdiction of the Mosaic Law? (631 commandments) Ignorance! We are tempted to worship Jesus under the banner of a plurality of religious ideas and superstitions instead of knowing what the Word teaches and what the Spirit confirms. (Read the gospels, read the book of Romans, read Galatians, read it all!)
The 10 commandments (plus all the other commands) are good and holy. They still stand as a revelation of God's holiness today. However, God uses His standards to expose the sinful heart of mankind. And having revealed what sin is, He has revealed His Son as the perfect, sinless, substitute for our "right-standing" before Him. Jesus has fulfilled the requirements of the law. Call to Him for your right-standing before God.
Bottom line? Trust Jesus as your sole source of salvation. Jesus plus nothing! (Not Jesus plus the 10 Commandments or your own ability to live "good enough".) Do not be deceived into thinking you contribute to your salvation or that you should place confident in the flesh. Your own righteousness is like filthy rags, you mess it all up! Jesus Christ is our salvation! His work of redemption will lead you into obedient behavior! You will experience the work of the Spirit as you are led to pursue the gift of holiness. You are dead to sin in Christ and your struggle with sin becomes a signpost to the glory of God at work in your mortal body. You won't have to worry about "losing" your salvation because, unlike the Pharisees, you admit that you cannot earn it; therefore you cannot lose it. It's all about God and His glory, not yours!
Gal 2:21 I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!