At most, the problem is with people reading into Scripture what isn't there, which is a fundamentalist no-no. So what you said would kill fundamentalist Christianity will actually do nothing more than reconfirm one of it's main principles against imperfections introduced by some followers.
Looks like I win.
I don't care about it because I think all "Religions" are wrong.
Really? I'm stunned.
Too many different beliefs between good honest people who are absolutely, positively convinced that theirs is the one true faith.
The New Testament says in several places that most people are going to Hell. So a non-Christian majority is exactly what you'd expect if Christianity is true.
Besides, atheism and agnosticism are beliefs about religious matters too, so your argument collapses in on itself.
Only if you think I'm lying about what the Christian I am speaking of said to me...In which case, you don't matter and are just looking for some kind of argument.