He said proof. Not just a theory. As in it's been proven that all the religions are wrong. Besides, how is it weak for them not to accept that their religion is wrong? Just because a religion is proved to be wrong doesn't necesairily mean it proves that there's no god. It could mean that all the religions simply interperited it wrong.
And how exactly can anybody find proof that all religions of the world are false that everyone would unanimously accept?And even if it were possible to find proof,every religious group would try to cover it up.
I'm an orthodox.And from the point of view of an Ortodox,I say there is a Father who is the Creator,a Son,who is the Saviour(Jesus is not as important in Orthodoxy as in Catholicism),and A Holy Ghost who is the Sanctifier of all.If Christianity is proven to be wrong,doesn't that mean that the basics of it would be wrong as well?And what do most religions have in common?A higher force that controls everything through its infinite will.That is what it would prove to be wrong.So,yes,it means that it would prove there is no God.
Also it means that everyone would have to reevaluate absolutely every value that regards their belief,which nobody would want or do.
What if god made him/her/it's self known to the people of the world?
Some would take it as a sign of Armageddon and run for sanctuary,some would start praying,some would dismiss it as mass delusions,so,to make a long story short,people would be feeling very conflicted about it...even in the face of overwhelming evidence.
What if 9/11 never happened?