This reminds me of a logical paradox: "There are no more killers on this island. Yesteday we executed last one."
Point is, if you punish someone, does it necessary make you evil? Or if you're just trying to make justice upon the wrongdoer?
In human society i think we are used to punishing wrongdoers by containing them in the prisons for amount of time equal to the severity of the crime. Is that action evil? It is, if you're imprisoning innocent person, but it is in interest of society if you do it to the wrongdoer, and it is called justice.
And "Burning in hell" is the absolute form of christian justice, reserved for the ones who have done wrong to other humans. But that also implies that you can't burn eternally in hell, because the punishment should last for amount of time equal to the severity of the crime.
So at the end, we might conclude that evil wellcomes evil, but at the end it will be treated with justice.