I am running a campaign during which all the gods left for various reasons. Because of this, I changed up the Paladin and Cleric classes, by providing an alternate source of power for paladins which changes some of their mechanics, and by providing an alternative class in the form of alchemists for clerics.
At this point, nobody had a cleric or paladin player, and none of the players had shown interest in playing one up to this point, so I thought I would have no trouble.
Most of my players are fine with this and are looking forward to the new setting, but one of my players says that Clerics do not need gods to cast spells and won't quit arguing about it with me. I disagree, and I have tried reasoning with him, but nothing is working. Any suggestions on how to get them to stop arguing with me, or any other solutions?