Religious institutions have openly opposed most major scientific, cultural, and medical advances that have occurred over the last 2000 years.
Whilst each religion thinks it has the key to enlightenment, they generally oppose enlightenment of humanity through scientific advance, because every time we explain an aspect of life through science, it takes away another bit of institutional power. Thus religious fanatics resist each advance, and that slows our progress.
It is difficult to quantify how much progress has thus been lost, because every advance in science and thought comes, to paraphrase Newton, from standing on the shoulders of the giants that have gone before. If the inquisition hadn’t suppressed the mind of Galileo, just as he was making his greatest breakthroughs, we might have gained fifty years in scientific thought. If they hadn’t burned healers at the stake, we might already have a simple cure for cancer. If they hadn’t suppressed the expression of independent thought with their threats, punishments, and wars, we might have a far more humane society by now, and a world at peace.
Religions, as a rule, always seem to think that the most recent concession they have had to make to science, and even to civilised society, is the last one. But religions of today have a long way to go before they catch up with civilised society. One thought consoles about ‘martyrs’ who blow themselves up for the glory of God and the seventy-two virgins awaiting in paradise - may they all be old hags.
What would it take to bring peace to the world over the next hundred years? Since it seems most unlikely that we are going to get rid of religious institutions and their perpetuated myths and discriminations in such a short time, it would be good if those with influence could at least make it a goal for their institutions to preach tolerance and compassion from their pulpits.
If the history of Judaism, Christianity, or Islam is anything to go by, the process of civilising influences will be painful and bloody. As people become less credulous, through education and the spreading of scientific awareness and knowledge, religions that still have life and death power over their herds of human sheep will use everything in their power to stop the spread of knowledge. In the end though, knowledge will win, as it always does. You can stifle it, and it will grow in secret. You can kill those who teach the truth, and others will teach it later. Science always wins in the end.
If you don’t believe that, look at every battle there has ever been between church and science. Knowledge is unstoppable. But the fact that it’s a fight; the fact that there is an ongoing struggle to civilise our world in the face of the ignorance and superstition perpetuated by the churches, and in the face of the vested interests of preachers and institutions who rely on the ignorance of their congregations for their income, now that’s a bad thing about religion.