Eilistraee.com

A long while back, I conceived of a cleric who survived a terrible battle, only to go somewhat... [i:pqpka34x]childlike[/i:pqpka34x] to put it mildly. Her alignment is still Chaotic Good and she still follows Eilistraee; she's not really a danger to anyone- She'll do totally off-the-wall stuff, but she's merely an inconvenient annoyance.

...now would that um... [i:pqpka34x]mentally unstable[/i:pqpka34x] person still be able to call on her cleric ability, penalty rolls aside? Would she still be acknowledged by Eilistraee?

You have not indicated anything that indicates falling from faith, as such she should still have access to all Clerical abilities.

Of course depending on feeble minded the character is. Wisdom should be lowed to under 9 from the sound of it, Int likely temporary reduced as well.

Insanity is covered in the DMG [the 1st 3 editions at least ] and depending on the form in which it manifests, that would affect the clerics ability to manifest their deity's power via prayer/clerical magic.

In the case of the priestess being reduced to a childlike mind, I'd suspect she'd lose her divine spellcasting but still have a [b:2ty74x3a]childs [/b:2ty74x3a]faith in Eilistraee/.

Well, I know that paladins retain their abilities unless they act in a manner which violates their gods' dictates. I should imagine it's much the same for clerics, only with more rigorous standards. If she still observes the proper conduct of a priest and is willing and able to pray each day to renew her spells, I don't see why not.

It really depends how childlike she's become.

It also depends on class. There are classes that use Charisma for spellcasting. So such cleric can be insane and be able to cast spells, no?

Yes does depend on the effect caused results.

I will mention the CHA based power n the later edition, the power comes more from leadership and less from how pleasant a person is in appearance and sound. How childlike we do not know, however it is rate that many adults would look to a child as a leader.