Luke 13:3:
"I tell you, no! But unless you repent, you too will all perish". For me, this is one the more difficult Bible passages to figure out.
Repentance requires the knowledge and acceptance of wrongdoing. If you are doing wrong and don't stop you will perish. That's understandable. But, sometimes
retrospection doesn't reveal wrongdoing until it's too late.
Take for example, how we treat the environment. Many social and religious assumptions are
anthropocentric in that they postulate human beings to be the most important and morally superior species on Earth. The environment and other species are there for mankind to exploit and to dominate. If you hold an anthropocentric
world-view, retrospection does not reveal the wrongdoing to the environment and other species, and hence there is nothing to repent about. And yet, "perishment" of the whole human species is an increasingly
real possibility.
In my opinion, religion is mainly about coming to the awareness of one's most unconscious "assumptions" about the world and of reality. Without this "awakening", one never fully knows what to repent for. Religions and spiritual practices not only provide verbal hints on what to watch out for and where to start, they also introduce ways (practices-rituals) of becoming more aware of your unconscious assumptions. Albeit, with varying degrees of success.