Can we keep all the Ten Commandments? No, no fallen human being can perfectly keep the Ten Commandments, and perfect obedience to them is not the means by which a person is justified or saved. This is central to the teachings of sola fide. “For all have sinned and fall short of the glory of God” “None is righteous, no, not one… no one does good, not even one” Jesus intensifies the commandments in the Sermon on the Mount, showing that anger equals murder in the heart, lust equals adultery, etc. Perfect outward compliance is still insufficient; the heart must be pure. Even regenerate believers, indwelt by the Holy Spirit, still struggle with remaining sin. Perfect, sinless obedience is possible only for Christ, who alone “fulfilled” the law. Full conformity to God’s will is the goal of glorification, not the present experience of any Christian this side of heaven. Is keeping the Ten Commandments needed? It depends on what is meant by “needed”. For justification / being right with God? No.
Justification is by grace through faith alone in Christ’s finished work. Christ’s perfect obedience are imputed to the believer. As the ongoing rule of life for the justified? Yes, in a secondary but real sense.
Believers are freed from the law as a covenant of works, yet the moral law remains God’s good will for how His people should live. Failure to pursue obedience is evidence that faith is not genuine, but the obedience itself is the result of justification, never its cause or ground. No one can keep the Ten Commandments perfectly, which is why we need a perfect Savior. Perfect keeping is not required (or even possible) for justification. Yet the commandments are not discarded; they continue to reveal God’s character, convict of remaining sin, and guide the grateful obedience of those who have already been declared righteous by faith alone in Christ. Jesus’ fulfillment of the law Jesus declared, “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them”. Christ perfectly kept the entire law - moral, ceremonial, and civil - in our place. His lifelong righteousness is credited to those who believe. He bore the curse of the law that we deserved. The cross satisfies divine justice against sin. The Ten Commandments expose our need; Christ fulfills their every demand; faith alone unites us to Him so that His obedience and sacrifice become ours. Because Christ has fulfilled the law’s demands, the believer receives a complete righteousness that is not his own. Faith is simply the empty hand that receives this gift. The law is therefore not set aside; it is honored and completed in Christ, and its benefits are applied to the ungodly through faith alone.