Cursed be Canaan;
A servant of servants
He shall be to his brethren.”
When God curses Canaan through Noah, He defers His judgment taking effect for several generations. Canaan the son of Ham does not actually become a servant until Joshua conquers the Canaanites. Until then, they roam free in fertile territory, enjoying a lush land. Abraham is subject to them and he and Isaac have to fight for well water with the Canaanites.
God often waits to execute His judgments, even for generations.
Two lessons come from this for believers.
1. Be vigilant.
When you fall into sin, do not get careless about it if God doesn't bring you up short in some way right away. As with David who remains in his sin for a while, covering it up with various devices, God waits a while to show you your depravity and give you opportunity to repent. Do not take advantage of His forbearance.
2. Be patient.
When you see wickedness go unpunished, don't fret. This is God's way, to allow them their moment. He is giving them a chance to stop it, too. I heard today of a Supreme Court opinion in Casey v. Planned Parenthood by Justice Kennedy that "at the heart of liberty is the right to define for one's self the meaning of life and the mystery of existence." This is wicked, but it rules our land. God will judge it in various ways, even if He does not use the direct form (impeachment?) we might want to see. Be patient. God knows what to do and what He is doing with this nation of His and His world in general better than we know to do.