However, there is objective evil. ISIS is objective evil, for example. Russia or the USA are in the gray zone, where some of they actions are evil, some others are simply stupid, and some other have sense. So, I understand your point, everything is complex, but we should avoid losing our moral compass. Some evil is really evil.
I guess that all most religions and philosophies would agree in that causing unnecessary pain is bad, that to kill for pleasure is bad, etc. It is difficult to explain in words where the common denominator is, but this doesn't mean there isn't one.
Edited: typos.