I'm talking from the perspective of modern people like Newton. They didn't consider a good God to engage in morally bad practices like lying and misleading.

There are places in the Bible where it sounds very much like God does not want to be clearly understood. I seem to remember a verse (I don't recall which book it's in...) where Jesus says that he speaks in parables (as opposed to plainly) because otherwise most people would understand him. The general argument I've heard is that evil serves a purpose, and perfection according to God requires the experience of lots and lots of bullcrap. The obvious question is why he wouldn't then create people with those experiences built in...