mathoda.com

Think of religious ideas as mental frameworks that live in the mind. Like natural organisms, a particular religion can demonstrate more fitness for spreading from mind to mind in a particular social environment then another.

Over many generations, certain religions dominate and others recede. Some will mix into their framework new ideas, mutating like natural organisms into a form the orthodox detest but new societies find more palatable, and others will remain unchanged. Partly the fitness of a religion in any social environment is its fitness to spread to nonbelievers, partly the fitness of a religion is its ability to hold onto existing believers, and partly the fitness of a religion is the power and ability the believers have to really influence the nonbelievers.

Living in a society that protects (even if it sometimes discourages) the freedom to believe what you will, it is common to think of the decisions people make about what religious beliefs to hold as personal choices made based on the intrinsic characteristics of a religion. Yet if you think about it, for much of the time religions have spread across human minds, one religion has tended to dominate in a geographical area, and since people often didn’t move far from where they were born, their social environment was much more harsh or unforgiving to making a decision about following a non dominant religion.

Here’s an interesting display, over time, of the spread of the world’s dominant religions.

http://mapsofwar.com/images/Religion.swf

It unfortunately doesn’t show the non dominant religions and it doesn’t show smaller religions that dominated much smaller regions. It also makes you wonder what religions existed hundreds of thousands of years ago, while our species existed, but before they had started to write their beliefs down.

Nonetheless, watching the history of the spread of dominant religions is interesting. It makes you realize how much a person’s current religious beliefs are shaped by ancient conquests and the accident of the geographical location of their ancestors.