I think that when you said they can't even agree on their own BS that summed it up up just right.

Thankfully I haven't been to a Barbers Shop for 19 years now.
I shaved my head in 2000 in support of my daughter losing her beautiful, long blonde hair during Chemotherapy and have kept it shaven ever since in Honour of her memory and to honour all the others who have endured/will have to endure/have passed from cancers,etc.
But, it's not only in Barber Shops where one get accosted by the 'faithfools,' I've copped it on the buses, at bus stops, in the streets, in Supermarkets and even in Coffee Shops whilst trying to just enjoy a quiet cup of coffee, I can sympathize and empathize full well with the sentiment expresssed in the O.P. and would add that, in my opinion, NONE of those sects of the 'faithfools' could ever manage to come an agreement on even the colour of shit, let alone who is right about their Invisible, Imaginary Sky Daddy Friend.

The book was written by men, and sometime after the events. Then translated into lots of different languages with changes as understanding of dead languages becomes ever uncertain.
Then consider the expanse of space. "If you think it's a long way to the shops, that's nothing compared to space" (Adams, D. Hitch Hikers Guide to the Galaxy).
What if God is busy with other creations? There are over seven-thousand million humans, he's got to be quite busy making interconnected plans for each and every one of us. Then why make so many of his children atheist? What about all those humans who died before God was invented? Did they get to heaven? Bringing new life into the world, then stamping it out again and all at faster than light speeds! Imagine the millions who are praying to him every moment of the day, no wonder he never answers!

The Jewish religion is the same way. Too many ways to worship a fairytale.

One of the things that helped me recognize that Christianity was not true was the infighting. Apparently, believing in a God that chooses you over others because of your worship in him leads to thinking that you are better than others, that your way is the right way, and that you need to save others from themselves. Who would have thought?

Cult members looking for converts love captive audiences! And if you are sitting in a barber's chair, you are temporarily at their mercy. Fortunately, where I live, there is but one barber shop. And the main topics of conversation are the weather, and fishing.

The reason they can't agree is because they have no means or method by which TO agree. When you believe weird things on no evidence, eventually someone in your group is going to tweak things because of taste or style or to get away with something or stop someone they don't like from doing something. Then they argue, no one appealing to any type of objective evidence or method to find out because none of them did that to start with.

It's like arguing over who is the best baseball team when no one bothered to make up any rules to the game, and half way through everyone decides to make up their own rules that don't agree with anyone else's.