This is my understanding

Disclaimer: I am not a Christian. I am attracted to this subject from the philosophical and psychological aspects of it.

1. For what happened, accept that there are things we mortals may not be able understand why it happened. There must be a reason, we just don't know it yet.
2. For other people, don't judge them, don't criticize them, accept them.
3. For oneself, acknowledge we are all fallible therefore we should be humble. Forgive others as we all need to be forgiven, because we all make mistakes. Forgiveness is not the same as take no responsibility over your own action though. For every action, there is a consequence. The suggestion of claiming that you are Christian therefore you can go to Heaven no matter what you 've done is a cheap joke.
4. Live your life by following the doctrines defined by Bible/Ten commandments...