Since all are to be judged according to their works, what if one claiming to be Christian has no works to show when God clearly expects them? James 2:19-20 clinches the argument: "You believe that there is one God. You do well. Even the demons believe - and tremble! But do you want to know, O foolish man, that faith without works is dead?"
This entire issue is actually quite simple. No amount of works can justify us before God. Justification by faith in Christ's atoning blood makes one legally free to access God and to begin a relationship with Him. However, from that point on, works are absolutely required for sanctification unto holiness - to the extent that, not only is one's reward contingent upon them, but also salvation itself. Will God reward one who can show no works at all, or provide salvation to one whose faith is so weak it produces bad works? Such a person would be totally out of place, unfit for living eternally in the Kingdom of God.
Ephesians 2:8-10 makes this reality even stronger. Even though we are saved by grace through faith, the very reason we are created is for good works that God Himself prepared beforehand for us to walk in. The gospel of the Kingdom of God provides the reasons for which works are required - the major one being to prepare us for living in God's Kingdom.
God intended Israel's forty-year journey through the wilderness to prepare them for living in the Promised Land. However, even though Israel had the gospel preached to them and had godly leadership provided by the likes of Moses, Aaron, and Joshua, in their stiff-necked unbelief they refused to submit in obedience to God's commands. They thus failed to receive the necessary preparation for using the Promised Land rightly, becoming an eternal example of why works of preparation are needed (Hebrews 4:1-2).
Can we learn a lesson from their examples? When God brings us out of spiritual Egypt, He is not done with us yet. In fact, a great deal of spiritual creating within us remains to be accomplished before we will be fit to live and occupy a working position in God's Kingdom. We are being created in Christ Jesus, created in His image. Can we honestly say we are already in His image when we are merely legally cleared of sin? Absolutely not! As great as this is, it is not the end of God's creative process. God is not merely "saving" us. His purpose is far greater than that.