Would it be reasonable for a Winter Witch to also be an Evangelist, with the Aligned Class being the PRESTIGE Class Winter Witch?

[Reksew_Trebla]

I may be reading this wrong, but the Evangelist Prestige Class doesn't seem to say you can't choose a different Prestige Class as your Aligned Class. Since the Prestige Class Winter Witch is also advancing a lot of the features of the Archetype Winter Witch, doing this would be like advancing 3 different classes at once.

Obviously it isn't actually as powerful as advancing 3 classes at once, as not everything is gained from all 3 classes, but it just seems like a no brainer, if you actually have a deity that would work well with Evangelist that is.

Am I crazy, or is this a good idea?

[I grok do u]

You can do this. You do get all the class benefits as you see. You'll end with effectively witch (winter witch) 19/winter witch (PrC) 10/ evangelist 10.
Levels taken: Witch (winter witch archetype)5/ Winter witch (PrC) 1/ Evangelist 10 (Aligned class: winter witch PrC)/ and back to witch (winter witch archetype) 4 levels to character level 20.

Some trade-offs are:
The first level of Evangelist will lose a spellcasting level that can't be replaced, so you're always down 1 level of spells after entering evangelist.
Evangelist boosts BAB, but swaps WW's good Will saves to good Reflex saves instead.
Gotta worship a deity with evangelist option available, and do the daily obedience - every day - or lose evangelist class abilities, including any aligned class advancement.

[DeathlessOne]

Its a perfectly valid combination, provided your GM is allowing prestige classes to begin with. Be sure to run the idea by them. Prestige classes are explicitly called out to be under the purview of the GM in the Core Rulebook.

[Tom Sampson]

You can do it, but it's probably not a good idea, because you still lose a level of progression on all your class features, including spellcasting. The Winter Witch prestige class also loses a level of spellcasting progression, but you can use Prestigious Spellcaster to remedy that. Typically the losses will exceed the gains when it comes to using the Evangelist prestige class. For a full caster, being behind 1 level of progression means that 50% of the time you will be missing access to your highest level of spells. It's a very big difference in performance, so you shouldn't do it unless you get something really strong for it.