Typically the Lord says this after announcing an upcoming judgment against a nation: "Then they will know that I am the Lord." My question: Did the events of 9-11 return America to God? The answer is obviously no. The people of our nation have continued to rebel against God, going so far as to pervert God's most fundamental sacred institution: marriage.
This rebellion itself is the judgment of God in part. All throughout Scripture we see a recurring theme when God judges a nation: wisdom is stripped away from its leaders and its people. Only wicked governing authorities would show such disdain for the God under whose authority they serve. And only a wicked nation would continue to elect such people to lead them.
Even we who are God's people -- the church -- are not unaffected by the wickedness in our nation. Daily we are tempted to listen to Satan's lies, to doubt God, and to devote our hearts to idolatry. We must remind ourselves that embracing the world means rejecting our Lord.
There is a greater measure of God's judgment coming. It may continue to be the slow burn of a people whose minds are given over to their own debased desires (cf. Rom. 1:18ff), or it may be a swift and devastating series of calamities. In the end, then we will know that He is the Lord.
May we judge ourselves so that we will not be judged.