Abetting an evil is encouraging it and giving it your approval. It is watching the evil occur and doing nothing whatsoever to stop it. It is seeing the evil destroy lives, yet refusing to offer assistance to the victims.
It is hearing about all the evil taking place througout the world, and giving it little thought, and no prayer. It is choosing to be a spectator when front line warriors are desperately needed. It is saying "no" to God when he calls, yet expecting to see his kingdom progress.
The Lord God Almighty El Shaddai