"Great evil" refers to a severe and morally wrong action or behavior that causes significant harm or suffering to others. It can describe something very bad or wicked.
Sentences with «great evil»
We attempt oft - times to realize a greater good in one respect at the price of greater evil in another respect. (religion-online.org)
This is not in the least to suggest that human beings are not responsible for great evil in the world. (religion-online.org)
Some of these were forces for great good, but in others lay the potential for great evil. (firstthings.com)