Your Kingdom Come (Matthew 6:10; LD 48)

When you read the Old Testament one of the great hopes is that when the Messiah arrives the kingdom will be fully established.  It is clear that when Christ walks this earth that the kingdom of God is at hand, but there is still something that is not finished.  If the kingdom has come with Christ entering history then why do we pray, “Your Kingdom Come” if that kingdom is already here?  How can we rest in Christ’s work if the kingdom is not fully here as Israel expected?