While a complete explanation of the origin of sin eludes us, there are a few things we do know. In His sovereign wisdom God has permitted evil to exist in carefully restricted areas of His creation, a kind of fugitive outlaw whose activities are temporary and limited in scope. In doing this God has acted according to His infinite wisdom and goodness. More than that no one knows at present; and more than that no one needs to know. The name of God is sufficient guarantee of the perfection of His works.
– A.W.Tozer; Knowledge of the Holy; Kindle Version; Page 88