I was going to say anything with any kind of scripture. I see it was posted long before so I am not quoting, but I'd like to repeat that. Anything related to any kind of religious doctrine; Abrahamic religions, Eastern systems which people don't like to define as religions esp. in the Western cultures, new ones...unofficial ones...etc until the age of 18.
So by all means, please let everyone read all of it, but after they grown out of an impressionable age. I wish we could prevent them reading these until the age of 25, but alas... Then let's see how many believers, religious people will remain on the planet, just in 50 years of time span.
Because if we please drop the political correctness, making children 'reading' this stuff, 'teaching' this to them is not done for providing them any 'readings', unless you are raised in a secular, actually an atheist household and given these texts as some piece of general information with some context. (I am not even mentioning schools, public or private, education should have nothing to do with religions or belief systems.)
It's nothing, but indoctrination. It has nothing to do with freedom of religion or belief. Freedom is about choices. This is done so they wouldn't be free to choose a religion or belief, but one. Because that's the basic point of religions. It's done, because it doesn't work in any other way. You can't do that to an adult raised away from any kind of religious tradition.
So yeah these are the first books that comes to my mind that children shouldn't read. They should be shielded from all these. Adults can read/watch everything.