curse
If no one else, we ought to blame God. But with the His death, we now have no one to blame except ourselves.
This is the tragedy of the modern man. He shoulders a responsibility that he will not, or perhaps can not, fully comprehend. And yet it he must contend with it until death. It is the responsibility of playing God in a godless world.
In a world with God, He assumes responsibility of everything. Man still has free will, but even the will of man is granted by God, thus becomes his burden to bear. And being His responsibility, He is the one that smites mankind when they fall out of line.
Without God, all of this responsibility falls to us. We are wholly responsible for our lives, most of all in pursuit of happiness, which also used to be a God-given right.
We are responsible for defining for ourselves what it means to live the "good" life. But having done away with good and evil, what framework do we have for establishing this at all?
WWII was perhaps the last nail in the coffin. The fact that man could commit acts so evil, so barbaric against his neighbor suggested that there is no God or that He does not care. This idea of absolute evil, forbidden by the Law, was shattered.
Man had free will to wreak as much calamity on this Earth, as long as he had the power to do so. And to contend with this truth, this truth that such evil could exist, we became moral relativists.
That under certain situations, people could act in evil ways without knowing that it was evil. And this is how good and evil retreated into the background, and we were left with nihilism to cope.
There is simply too much moral responsibility on our shoulders for us to bear, so we did away with it altogether.