What do you mean by intellectual development? This type of question often leads to ahistorical assumptions. The world wasn't always as secular as it is now. Religion wasn't some separate category, it was a part of everything. Science and philosophy were ways for mankind to learn more about Gods creation. So you could certainly say that Christianity inspired men to try and learn more about nature and explore their own thoughts. Tension sometimes arose when certain scientific discoveries or philosophical works were in contradiction with Christian morals, but usually these were resolved by adapting said theories to Christianity. Thomas Aquinas is an example of a philosopher and theologian who spent much of his time trying to make peace between Greek philosophy and Christianity. The same kind of process can be seen with many scientific discoveries, where they were often first met with opposition, the resulting discourse within theology often successfully integrated these theories within Christian theory. It's certainly true that the church acted harshly against certain scientific discoveries, but more often than not this resulted in a very productive debate during which scientists, theologians and philosophers try to reconcile these new theories with Christianity. Again, there was no clear distinction between several disciplines nor between secular and religious interests.

Also, I would thread lightly when reading websites like the ones you posted. These were clearly written with a personal agenda in mind and are not subjected to proper historical practice. It's safe to say that contemporary historians are moving away from the stigma of "Dark Ages" and are recognizing the richness and importance of the early to late medieval times.