The Crusades left millions of Muslims and Christians butchered. The Catholic Inquisition is estimated to have burned at the stake 9 million so called "heretics". This is even worse than Hitler's 6 million Holocaust victim. The Catholics and Protestants are still at each other's throats in Northern island. Add to this, the Muslim suicide bombers and their victims. The 9/11 twin tower incident would not have happened if not for religion.
On many occassions, in the annals of human history, religion has transformed otherwise normal human beings into mad men, killing for the sake of his God. Added to all these is the well-reported scandals involving priests committing Pedophilia and the systematic effort of the church hierarchy to cover up the said crimes.
Organized religion has failed humanity. The great cathedrals of Europe have now become mere tourist spots because faithfuls don't go to church anymore. Man has become secular rather than spiritual.
The latter half of the 20th century had seen many of the greatest minds turn away from religion. When it comes to God, this past 100 years or so, many people and some of the brightest minds are rejecting God than any other period in church history. Sir Isaac Newton declared that everything he observed was the work of God. Yet less than 300 years after Newton's death the top minds in the world are wondering if there is even a place for God in a self-contained universe.
We now know so much more than we used to. Man's knowledge and his mastery of the natural world made God unneccessary.
Is mankind better off without religion?
Photo taken here.