Really? Has human nature changed since the fall of Adam? Do you believe in Adam?
It is, frankly, an uneven progression with lots of reverses over the centuries, but socially things have progressed.
Have you been to Africa or the Middle East? How about Pakistan or Iran? Are they improving socially? In the last century over 100 million people were murdered by tyrants and governments in Christian nations such as Russia and Germany. Was that an improvement over the previous century? You think this century is going to be any better?
What God is doing is slowly bringing us to a more complete understanding of Himself and His will.
There are less and less Christians every year. We are moving towards an Islamic takeover of post-Christian Europe which will be followed by an Islamic takeover of post-Christian Canada. Are you suggesting that maybe "Allah" is God? Or are you just engaging in wishful speculation?
Human nature doesn’t change, as in we cannot change it ourselves. But, if we allow God to work through us, then we can progress as individuals, and through our subsequent actions, affect an ever-widening circle of people, which eventually reaches the whole of society.
100 million people murdered by tyrants and Governments in Christian nations? Surely that is an inditement of tyrants and governments, not Christians. Christians have never claimed to be any better than anyone else. The only thing I have going for me is a savior. So if you say “oh Christian countries have murdered x number of people” as some kind of clinching argument - well, hands up, straightaway, guilty as charged. But then, what is a Christian nation anyway? I think you mean a nation where a majority of the population espouse Christianity, but as a minority of people even in the US attend church every Sunday, that doesn’t really mean very much. Christianity is not some kind of social club, or cultural allegiance fraternity (or at least it shouldnt ONLY be that). Christianity is ultimately something that you do (more accurately, its something you respond to).
The light of Christ is dim over the middle east at the moment, and so their societies have darkened, but I still say that where the light of Christ has shone, Humanity has progressed. The western world has given up on slavery. It has adopted the rule of law, rather than the rule of force. It has due process, it has security, it affords its citizens rights instead of just responisibilities. The bleak side of Human affairs seems more prominent because it gets all the publicity.
I would suggest you are indulging in speculation yourself my friend. No one but God above knows how many people are or are becoming Christians, because only He can see inside men’s hearts and souls. What we are seeing is not a post-christian society, but a post-christendom society, and its not altogether clear that Christendom was all that good a thing anyway. As you implied, tying faith to politics is always a bit dicey (as witness Islamists today).
I do not believe that Islam will be ultimately triumphant. It’s a matter of faith you see :)