Romans 12:21 is preceded by information (Romans 12:1 thru 12:20) regarding the nature of Christ consciousness and Union with God or the Experience of God in awareness within ones Self/self and everything one experiences. And it also covers the effects of Karma or cause and effect. (vengeance is mine sayeth the lord) Evil or wicked action being action of Ego creating repetitive lifetimes of reoccurring experiences based on the limited realization of reality until one discovers the Truth to end the cycle of ignorance.
It (enlightenment) is the very prerequisite to overcoming evil (EGO), and the only way to (As stated in 12:21) to be not of evil but to overcome evil with good.

That would be what Tolle means by being aware of the underlying current of reality, and evil

I was addicted to the Hokey Pokey, but then I turned myself around!!