[dragonwriter]

> Eh, in some instances you can define extremeness relative to alternatives, not number of believers.

Relative extremeness, sure, but that makes something more or less extreme, not “extreme” without a comparative.

> Execution as a punishment is more extreme than a fine regardless of how many people favor execution over fines.

But execution for most serious crimes was for a very long time a standard position, not an extreme one, while not executing people was an extreme position (though it's now pretty standard in most of the world, with broad—or indeed any—use of execution being an extreme position.)

> I would argue that generally a position being extreme results in fewer believers, not that fewer believers results in a position being extreme.

If you would argue that, go ahead, but you've provided neither evidence nor much argumentation, just conflation of absolute and relative uses of “extreme”, and your example of capital punishment seems to disprove your thesis.