Religion is not "about enlightenment". Religion is about faith in unprovable dogmas.
The age of enlightenment is something that happened in the West, liberating the people from religious thought suppression. However, there are other religions which have never been faced with an age of enlightenment.
When you have a god's command about what is right (backed by the threat of an eternal bath in sulphur), there is no question of contemplating other viewpoints: they're simply wrong, and hellworthy - hence the whole 'unending religious violence' thing.