There were no such thing as 'muslim nations' during the middle ages, the nation-state is a modern invention. While it is true that after the fall of Rome scientific progress diffused from Islam to Christianity (a trend that would not be reversed until the Florentine Renaissance), none of the muslim lands were 'highly religious'. When Saladin left Jerusalem during the 3rd crusade, the focus of the Islamic world shifted from exultation of Allah to organizing the economic and political chaos left behind by the crusaders. The former crusading kingdoms of Antioch, Tripoli, Edessa, et al became a magnet for disaffected Christians and Muslims, who abandoned religious fundamentalism after centuries of bloodshed, favoring instead a return to the classical legacies of Rome, Greece, and Alexandria. Religion, during this time, was subverted in favor of science, a trend that led directly to the Islamic Golden Age (750 - 1300BC) and its advances in astronomy, medicine, trigonometry, and geometrical optics. The age of muslim enlightenment ended in the mid-13th century, when a rebirth of Islamic fundamentalism reacted against the intellectual elites by destroying libraries and madrasahs throughout the Middle East and North Africa, and plunged the muslim lands into their very own Dark Ages, which have arguably lasted until this day.
In the Christian West, the end of the Roman empire marked a return to tribalism, feudalism, and constant warfare, with religion often invoked as rallying cry against decadent excesses (and the scientific advances that made it possible). Philosophers and scientists were targeted as heretics, and either executed or exiled to the -then- more progressive Muslim East. For the roughly 1000 years of the Dark Ages, Europe 'forgot' the earth was round (something the ancients knew very well), practicing medicine was equivalent to witchcraft, alchemy (a precursor to modern chemistry) was branded as 'occultism', and the written works of Plato, Aristotle, Hero of Alexandria (who discovered steam power), Galen, and Ptolemy, once a cornerstone of civilization, passed into obscurity, and then into legend. It was only during the Italian Renaissance, which shifted the balance of power away from the Vatican into the hands of wealthy merchants, and so favored Humanism over Christianity, that science and philosophy rose again to prominence.
To highlight the idea that religion drove human civilization back into the cave, realize that almost all of the scientific 'discoveries' made between the Renaissance and the Industrial Revolution had already been discovered by the ancient world. The idea of the atom, the engineering of vast interior spaces, machines that increased productivity, free market economies, and state investment in infrastructure all had their inception with the Greeks, the Romans, and the golden age of Alexandria. This means that as a direct consequence of the religious fanaticism of the Dark Ages, human civilization is about 1000 years behind where it ought to be. The collective loss of reason experienced during that time set us back quite a bit. It is probably true that, had classical advances in science been allowed to flourish from 476-1400BC, we would have colonies on Mars by now.
TL;DR: the world is a shittier place today because religion was allowed to reign unchecked for way too long.
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