I would argue that, as with any similarity, religion is good for cohesion within a group who all believe in exactly the same religion. People are generally going to be more comfortable with people who are more like themselves than people who are completely different. The cohesion is often lost because eventually different factions form in most religions. (Judaism splitting to Christianity for example) This is because human beings have other attributes that fight against the cohesion and conformity found in religion.
Two of those qualities are creativity and curiosity, both of which are lethal to dogma which is a common thread in most religions.
Progress, however, requires a steady balance between the order provided by cohesive conformity, and the freedom that comes with creative curiosity. It seem that religious leaders, typically prefer to be the ones doing all the creative thinking though, which slows down progress tremendously.