Religion can be key to a person’s identity. It manifests both as an internal sentiment as well as in structures in a landscape. The religious world is always changing, but at a pace that is generally very slow. New religions are created, while other religions may fade away, or change. The general historical trend has been toward a small number of universalizing religions gaining ground over local, ethnic religions. Religious differences can lead to conflict, although many conflicts presented as religious in nature have their roots elsewhere. Just like language, religion is another way of sorting people into groups, either for good or bad. Another such way of sorting people is ethnicity, the subject of the next chapter.