The Dying Thief

What does the story of the cross tell us about how God in sovereignty saves sinners? What do the three who hung on the cross represent? How is the work of the LORD Jesus Christ and His grace toward the worst of sinners a comfort for those for whom HE paid the debt? How does the story of the saved thief illustrate that no sinner need despair of his case, and yet no sinner should presume upon the LORD'S mercies.