Does Religion Retard Human Achievement?

It might seem pointless to pose the question of whether religion retards human achievement to atheists since we pretty much already know that it does. So my question is not really to address whether or not religion retards human achievement ( it does), but rather to address whether or not it is possible that religious people can recognize that it does, and understand that it's this retardation that bothers most atheists, free-thinkers and progressives.

Most atheists in the West are humanists. On the American Humanist Association's website, humanism is defined as:

Humanism is a progressive philosophy of life that, without theism and other supernatural beliefs, affirms our ability and responsibility to lead ethical lives of personal fulfillment that aspire to the greater good of humanity.

Now humanism is not a default belief given the absence of religion. There are many other alternatives that can compete in a free market of politics, philosophies and ideologies. Humanism must therefore be arrived at through the use of critical thinking with the goal to seek the "greater good of humanity".

When I debate with conservative theists on the epistemology of truth, they all believe that the use of logic, reason and science, are inferior to the "truth" of revelation; meaning, if a supposed revelation gives us a claim to scientific or moral knowledge, even if it seems counter-intuitive, mankind's use of his critical faculties is futile, or in the case of Islam it is forbidden, to try to better explain events or arrive at better truths. So to the conservative theist, revelation must always supersede any amount of knowledge that contradicts it.

One of the most enduring arguments that Christopher Hitchens repeatedly made against religion, was that religion forces us to constrict our critical thinking abilities, - the most important abilities that we have, in favor of unproven dogma believed on faith. This is a retardation of human achievement if there ever was one.

But through all my debating what I have not been able to achieve, is to get any theists to admit this and say something like, "yes religion does hinder critical thinking, and that can slow human achievement, but my religion requires that I belief certain things on faith." If a religious person actually said something like that, perhaps with a difference choice of words but with the same overall message, I think it would be a milestone in the debate between reason and faith.

Instead of an acceptance that religion retards critical thinking, I get a bunch of history lessons thrown at me about Islamic and Christian scientists who made great achievements in math and science. For example, one Muslim debated me this position:

You still keep lying & saying that Islam retards Human-achievement, yet you have absolutely no proof of this. However, there are countless historical & contemporary proofs that the light of Islam has inspired Muslims to excel in the fields of history, science, medicine, mathematics, and the list goes on. In fact, the world-renowned “1,001 Inventions” exhibit, which highlights the technological achievements of Muslims, over the past 14-centuries, as well as the renovated Islamic-Exhibit at the Metropolitan Museum of Art, in New York City, thus proves how Islam helped, and even pushed people towards greater understanding of the cosmos, art, mathematics, technology, etc

Now I don't deny that there have been many people who believed in god that have made great achievements for mankind, but I cannot also forget that it was institutionalized religion in Europe and the Middle East, that feared many discoveries these inquisitive minds brought us because it contradicted long held assumptions founded on dogma. So I respond saying:

I fully acknowledge achievements made by Muslims during the golden era. But Islamic thinking (much like how Christianity was centuries ago) began to resent the critical thinking that lead to scientific and philosophical progression. Greek philosophy, which Arabs had preserved, became illegal to copy; the Ash’ari school of thought which still dominates Islamic thinking today, closes off the idea that human reason, science and observation can discover scientific & moral truths, and instead believes only revelation can do so. This is clearly evident in the way you argue. This lead in part to the decline in Islamic science and understanding, and the West, which had less restrictions on reason and logic, passed the world in all areas of achievement. So, if you do not have a free and open system, that allows all ideas to compete in a free market, where the best wins, you will retard human achievement. And Islams does exactly that.

When religion turned against the free pursuit of knowledge, many great minds were jailed, tortured, killed, and burned alive in the religious war against knowledge before, during and after the Middle Ages. Just because a person can be inspired by religion to pursue knowledge, doesn't mean that the religion as a whole supports an open platform for free inquiry if it also held down by unproven dogmas, as all religions have. 

Religious people do not want to publicly acknowledge the fact that religious dogma can hinder the pursuit of truth because they know that by doing so they will be admitting that religion acts like an anchor that prevents growth and thus retards our body of knowledge. That is why atheists like myself are extremely passionate about maintaining a system in which the free pursuit of knowledge, unchained by any dogmatic beliefs, continues to thrive.