Good points, but now we have technology to "shrink the world" as it were (with satellites, phones, computers, remote cameras, and other technology).
As for your question, "what is their achilles heel" that might be the wrong question. It's true that there is a supernatural answer: "The devil has already lost". But that might be the only answer.
Perhaps only a few people can't reverse the trend of human nature to want an easy, passive life, with a bad guy to hate, your own country to root for, constant war = peace, constant lies and propaganda = truth, etc. (just like the book 1984 -- which I hope you've read, Vandaler). Look at how few people are interested in figuring out the ugly truth at all! Most people "don't want to think about" anything unpleasant. That will play right into the hands of the baddies, and there's nothing we can do to wake THOSE people up. We can only reach the people who spend some time online, and are half-interested in finding out the truth. You can't make people love and want the truth.
In short, we can't exactly fix this thing on a "human level". That's the problem with guys like Hitler. He wanted to fix up the world on a "human level" -- let's populate the world with Aryans, let's get rid of those Jews who have been causing trouble for centuries, and we better get rid of any competing authority such as the Catholic church. Oh, and we don't want our society to crumble from within, so we better deal with the homosexuals as well.
It's a spiritual struggle, and it always has been. The "bad guys" are held together by a common hatred of the Catholic faith and the laws that God lays down for man -- though I'm sure there's a bit of selfishness in there, which will cause a bit of friction among themselves.
Still, all the prophecies say that the devil will snatch defeat from the jaws of victory. (Yes, I typed that correctly). Just when he thinks he's won, that will be his undoing. Look at what's happened in the past! You have the crucifixion, which was the closest the devil ever got to a victory (especially since mankind was at his lowest point meanwhile) -- but it was also his GREATEST loss ever. I think God's providence uses foreshadowing and better than any human author, writes a well structured story.