I live in N.Ireland and we have definitely been afflicted by a backward outlook for centuries. The whole island has been backward, but the north even more so than the south. This backwardness stems from religion. Up until relatively recently the south was basically run by the catholic church, while the north, also religious, has the added tribalism thrown in (Catholics vs Protestants...since the Ulster plantation).
This devotion to religion is regressive. It stunts growth (see the Arab world and the contrast between its vast contribution to human development before Islam and negligible contribution after Islam). The most backward part of the the US? The Bible belt (the same region slavery (owning human beings, like pets) thrived until a war was required to end it, where racial segregation was de jure (with a judge in 1965 declaring interracial marriage illegal in Virginia as, quote; "Almighty God created the races white, black, yellow, Malay, and red, and placed them on separate continents and but for the interference with his arrangement there would be no cause for such marriages. The fact that he separated the races shows that he did not intend the races to mix"), where today tens of millions of gullible folk hang on every word of a shyster (and an atheist, shush don't tell them) in Trump. The growns up on either coast keep that country functioning.
Thankfully, the island of Ireland as a whole has gone some way to shaking off the shackles of religion (the main exception being the free presbyterians in the north, the nutty folk who vote DUP and ensure we don't have a functioning government). It will take time, but we are slowly but surely getting there..I hope.
England (who declared theocratic Puritan legislation null and void in 1660) has long since ditched religious devotion, which is why the English tend to be the grown ups in the room. Free thinking thrived in England during the Enlightenment, and the critical analysis that comes with this form of thinking enabled it to question things, and with that comes invention and development (notably the Industrial Revolution).