Idioms are expressions that cannot be understood by their literal meaning. To avoid the things we are being mislead on daily preachings, we need to understand the Biblical idioms. We can just imagine the idioms that were then, two thousands years ago, that have changed along the way, and became into this. And once you come across with certain phrases and passages, the teaching may be misleading.
You shall not add to the word which I command you, nor take from it, that you may keep the commandments of the Lord your God which I command you.