Truth is hidden from those who can't handle it. Bible has a bunch of riddles and confusion in it because its made for the masses. The reason for chaff and wheat is to cause confusion as is the search for meaning. Its literally a game of confusion.

The cause of most sin is insecurity. The Bible instead of addressing that causes tons of insecurity and fear which cause people to do bad things. The Bible could say the reason you want sex is cause you are hardwired to and its much worse when sex is scarce, the reason you overeat, overwork, don't work, and drink is you are stressed and insecure. Instead the human is at fault.