Well... since I am a medieval scholar, I might as well try to help out a bit.
Again we have a subject in which we are trying to reduce a very complex situation into subjective dualism.
Obviously, Christianity had a tremendous influence on medieval (so to speak) civilizations in Europe and elsewhere. Despite claims to the contrary, that influence was not always negative, even though the negative influence could be remarkably destructive.
Much of the knowledge of the previous ages, particularly the Romans, was saved by a concerted effort by thousands of monks, constantly copying and recopying ancient documents. Most of the medieval texts I read tend to have been written by monks. During centuries of warfare and poverty, a lot more would have been lost.
However, the church, particularly the Roman Catholic Church, often also stood in stark opposition to science. I actually wrote a bit of a thesis in my third year (I think) about this duality. The church had a very conflicted view when it came to science. Some churchmen had a deep love of learning and a very inquisitive nature, in particular astronomy and mathematics but encompassing every field. The writings of the ancients was more precious to them than gold. Keep in mind the incredible depths of ignorance that existed at the time and how it must have felt to have a glimpse of a more enlightened world.
However, the ancients were pagans.. something that disturbed many churchmen greatly. Pagans were essentially devil worshipers in their view and to read their writing was to study the traps of Satan. Many churchmen actually considered new learning dangerous and probably a trap by the forces of evil. To them, the bible was the only book you ever needed to read.
It's of course quite a bit more complex, with individuals straying from the pack a considerable distance in either direction. Some churchmen were innovators in science, humanistic thought and sometimes even towards very modern ideals. Others displayed a vicious opposition to any deviation from doctrine, to a degree that can be quite astonishing. Try reading the "Malleus Maleficarum" if you want some scary bedtime reading.
The same applies to democracy. Of course democracy does not begin in the middle ages, and in fact the Catholic Church stood strongly against democracy pretty well from it's inception to the 20th century. However, a number of the ideas that form later on humanism do come from churchmen who espoused them and wrote about these thoughts at a time where few even knew how to read.
I think it's a huge mistake to demonize the church much as it's a mistake to ignore the horrible acts done in the name of God. Oversimplification is always a mistake when it comes to history.
