"The evidence for the existence of real evil is clear and manifest to everyone. That it needs to be opposed -- and often can be successfully opposed -- is also clear. What is not so clear is the existence of God; particularly a good God. In fact, religion is often a vehicle for evil too. Maybe this is a notion that we can dispense with -- or at least disregard -- in our quest for a better world."
Such is the line of reasoning of modern secularism and atheism. Notice the implicit sense of human autonomy in this view. The secular viewpoint becomes fuzzy, however, when you ask about its basis for deciding what is good or evil.