Joy changes everything, including our battle against evil.
John Piper explains in this two-minute video:
Christian Hedonism changes our combat with evil. Jeremiah 2:13 — the Christian Hedonist definition of evil — "for my people have committed two evils: they have forsaken me, the fountain of living waters, and hewed out cisterns for themselves, broken cisterns that can hold no water."
What's evil? The suicidal preference of empty wells over the river of delights flowing from heaven. That's evil!
So the battle against evil is not to constantly say "No, no, no. Bad, bad, bad." There's no power in that. The power of the flesh is coming at you, the power of the devil is coming at you, a…