Clerics in DF have the option to take Intolerance to "'evil' religions" or "all other religions" among their disadvantages.
So, what should count as "Evil" for the first one?
Here is one way to split that up.
Intolerance ("Evil" religions)
Evil religions should generally be capital-E evil, not just differently aligned from your own religion. Capital-E Evil religions should include one one:
- Worship of demons or elder things.
- Worship of gods who self-identify or are widely externally identified as evil, or an adversary, or malign. This may include death gods, if they or their worshipers go ahead making innocents dead, but may not, if they're merely fulfilling a role of neutrally taking those at the end of their time.
For the above, Intolerance ("Evil" religions) applies here.
Heresy probably doesn't get included. But it's right on the border. So when PCs start worshiping magical items (the cult of the Ebony Death Goddess, for example), the PCs are heretics but it's not clear if they are "evil" or not.
Otherwise . . . it's just an "other" religion. Intolerance (All other religions) applies to these cases.
Intolerance (All other religions)
This one is easy. If you aren't of the same religion, the cleric reacts at -3. Heresies will absolutely apply here - it shouldn't take Fanaticism to think that heretics are bad, IMO.
It's a little easy, especially in my Felltower game with a generic religion of the "Good God" to take all other religions as evil. You can do so . . . but you're shorting yourself points by not taking the Intolerance (All other religions) that really covers that case. So in Felltower the split above will apply - non-"Good God" religions, such as non-human religions, minor heresies, druidism, etc. aren't automatically covered as "Evil" religions for Intolerance purposes.