Following God: Ten Commandments

Do you know anyone who has never broken any of the Then Commandments? Unless you are thinking of Jesus Christ, you probably can's name a person who has kept every one of these foundational laws. Why did God issue these laws for Israel and mankind if they are so difficult to live up to? What relevance do these laws etched upon ancient tablets have for us today? For Christians living under the security of God's grace, how does the seemingly rigid and arbitrary nature of the Ten Commandments apply?