The greatest threat is spelled out in Psalm 9:17
The wicked shall be turned into hell, and all the nations that forget God
That is the greatest threat. A culture that has no fear of God, and no reverence of God. That culture is just circling around in the toilet, and waiting to plunge down into the sewer of history.
Sure, Islam is inspired of Satan, but I'm not going to blame them for our own faults. A Nation that embraces the celebration of sexual perversions, and that invites Islam onto its shores with open arms - has deeper problems than pointing fingers at Islam.
Dennis Prager has noted that in today’s America, “more people fear the Left than fear God.” That statement says a lot in only 8 words.