Ok, God is all knowing so why'd he let the snake in the garden?

The Problem of Evil that you just described -- how God can be all-knowing, all-loving, ever-present, and all-powerful, yet still allow evil things to happen -- is the biggest problem all religions attempt to answer. Christianity answers that "God has some bigger plan" or "God is teaching us a lesson" or "God is in control and we cannot understand how he works" or "we deserve the evil we face because we're all sinners" or other such things like that. It makes no logical sense. Other religions have eliminated one of God's four main attributes listed above, which solves the problem for them. For example, post-Holocaust Jews largely believe that God is NOT all-powerful, which leaves them with a loving, powerful God, but not one that is able to overcome all evil in the world. But for Christianity, it becomes a question of sacrificing faith for logic, which most people are not willing to do.