Act of evil? Or just taking out the trash?

[EvolutionKB]

I think it is your decision as DM. We don't really know how it went in-game. You can talk to your other players, as well as the player in question to see how it was received and how the player plans on playing this paladin(perhaps the paladin's player has played the thoughtful mage to this point, and that is why everybody else was so surprised).

Since saying "yes" is part of 4E, I would discourage making long term consequences(that is definable punishment for their actions), I would encourage further plot hooks for a paladin that may have strayed from Bahamut.

Things that make RP or encourage further adventures is good. Perhaps an agent of Bane or Tiamat has established themselves in Bahamut's temple. The paladin is looked down upon for a time and the evil doer leads them on quests against his own religion. Finally the PC is the one to uncover the corruptness of the temple and renews his good name.

 

[Ravingdork]

Whatever alignment he started as, let him know that if these types of acts become the rule and not the exception you will ask him to revaluate his alignment.

What I would suggest is that "the people" who catch word of this will likely be torn up about right and wrong much like most of the people in this thread. Just take some of what was said above, print it off/write it down and let the PC 'overhear' it when walking through a market place. No black and white here - just people arguing over it.

Jed the cranky old farmer: "Serves that sucker right, I lost family to people like him!"
Joy the gosspy fishwife: "Still draging him out like that, it doesnt seem right. Why not just kill him outright! That was torture!"
John town constible: "Right or wrong at least thats one more person who won't be doing bad deeds any more"

Consider his Superioures and/or his peers having the same kinds of conversations...

This. This I think I will do.

He *Added* something to the game, DO NOT PUNISH a player for adding to the game - reward them. It was a character defining moment, take it, use it, make it something of legend if you want. Heck it was a party defining moment - those are worth pure RPing gold!

QFT.