The campaign I'm running right now has a noble-kinda purpose: to kill the Evil Witch and save the world, etc., you get the point.
As a plot twist I am thinking of turning the campaign to being more evil. Not the kill-everything-on-sight evil; more like we-should-rule-this-world-avoiding-unnecessary-killing evil.
The Trouble: I proposed it to the players and 5 out of 6 agreed, and said that they'd probably enjoy it. However the one that didn't like the idea said that his character would stay Good, and that he would kill the rest of the party. He asserted that a Warden should be Good, and due to respect for Nature he wouldn't break the harmony unless it's mandatory to restore peace, etc. The player doesn't object to playing an evil character, he just feels his character wouldn't become evil.
He is the one who will probably get killed, but the point is that I wouldn't want them to fight with each other.
Finally The Question: How am I supposed to handle this situation?