Tempted and Tried

How does David's lies and fear reinforce the need for One greater than David, who was only a type of Christ to come Who would perform perfect the required righteous obedience to the law. Why did the LORD make the Sabbath day as a rest and a type of Christ the sinner's Rest? Why did God purpose David's enemy to be at that place at that time? Why did Christ have to suffer to make God a just God and Savior? When were the elect glorified? Is there really only one message in all of Scripture?