How do you test that? You cannot do a double blind test because you cannot induce religion in people to order.
> let’s see if we can take the good parts of the texts and throw the rest away.
I do not think you can do that. Each religion is largely shaped by a few key ideas. Remove one of those and you change it radically (losing the good) remove anything else and you will not change anything significant.
You can reform and improve religions, but I think history shows that is not easy nor are the results predictable.
I think you over-emphasise the importance of texts to religions in general. Texts are the foundation of American evangelical Christianity and (to an extent I am worse equipped to judge) Islam, but much of Christianity and at least some schools of Buddhism are really based in a very small core of ideas.