Someone suggested that the Canaanites were no different than any other nation, so why is it that God chose them for annihilation above others? Of course, the obvious answer might be that judgment comes to them because they are a threat to Israel who are entering the land. But, as I've argued before, it is not merely that they are a threat to Israel, both spiritually and physically, but also because their sin had been filled up.
Other nations, including Israel, are also destroyed by God for their sins, but all of it is when they have "filled up" their sin, a phrase God uses to express that He has let the sins of the people reach a climax before He completely destroys them.
But what does this destruction look like? It seems, from Scripture, that destruction takes place through the very choices of the people first. As Romans 1 indicates, they suppress the truth of God in unrighteousness and give honor and glory to gods more easily manipulated to accommodate their sin. It thus begins with the purposeful belief in one or more distorted deities, an antigod or antichrist who replaces the real God in one's worship. We can view this as the rejection of the seventh day of creation, where God rests in His cosmic temple as exalted above all creation.
So we are told, as a result, that God gives them over to begin a path of self destruction. He does this by reversing the next six days of creation, and the first step in creation's reversal is to engage in unproductive sexual acts. This is because unproductive sexual acts are the opposite of God's command in creation to "be fruitful, multiply, fill up the earth, subdue and rule over it." Unproductive sexual acts reduce population rather than multiply it. It goes counter to creation, which has its pinnacle goal in filling up the earth with humans who represent God's sovereignty over chaos/disorder/"uncreation."
Hence, we see that the Canaanites not only worshiped other deities, but that their sexual practices were characterized by unproductive sexual acts (Lev 18).
Once these practices come to a climax in a society, it seems that the remaining creation days are reversed. Famine instead of fruit trees, disease from animals instead of a healthy balance to the ecosystem, war instead of a submission of chaos all bring a society to disorder and ultimately annihilation/nonexistence.
This is why and how the destruction of the flood occurs. This is why and how the destruction of the cities of Sodom and Gomorrah occurs. This is what happens to the Canaanites, and it is also what happens to the Israelites. We could go on to look at great Empires like Greece and Rome, but the point is that the wrath of God is not immediate fire from heaven. It is a slow and patient reversal of creation within a society and it begins with distorting who God is and the practice of anticreational sexual behaviors.
It is therefore true that a culture participates in its own destruction long before it is devastated by war, famine, disease, or fire from heaven. And it seems that God does not destroy a people immediately, but only when these things have come to a climax.
Hence, the Canaanites, after thousands of years, had come to their breaking point. The Bible portrays them as a people who were filled with idolatry and sexual depravity (even killing their own children in sacrifice, which is the ultimate symbol that the creation mandate was in full reversal within the culture). God merely completed the self destruction they started among themselves, and we are told that he did so because such a self corruption and annihilation is cancerous and spreads to suicidal mankind that is addicted to the pleasures of its own demise.
The scary thing is not the historical Canaanites, however, but the world as it exists today. We have become an idolatrous people, who distort who God is in order to accommodate our own sin. He is easily controllable with our making Him a God of acceptance and licentiousness rather than the God of love and grace that hates chaos and that which produces it. We are a people of unproductive sexual acts, well on the road toward our own annihilation. We sacrifice our children for the prospect of a better life. We are not only the Canaanites, we are the Canaanites who have had more warning and revelation than even the Israelites had. And that is scary, precisely, because it seems that the more revelation a society has, the faster disobedience speeds it to destruction--the faster the process of creation's reversal comes to its conclusion.
With the church enthralled in its battle against homosexuality, it must look to its own idolatry and sexually unproductive practices in repentance. Perhaps, abortion, gay "marriage," nuclear weapons from N. Korea, terrorist threats from Islam, economic collapse, etc. are merely the results of our own sin more than those of the unbelieving culture. Perhaps, we have sped up this process, and the fact that we are looking out at a Canaanite world is because we became Canaanites ourselves.