Although, there is nothing in the bible against pot.
In fact, I once met a guy who told me he was pushing a high court challenge against cannabis prohibition, on the grounds that in the bible it says "Ye may eat the herbs". If he hadn't been so totally out of it he might have heard my reply about the bible not having legal status here.
It isn't so much Christianity per se, as Wowserism in general, that is the problem.
(Wowser = fun police.)