Why should we avoid doing bad things? There are many good reasons for doing so.
1) There are always consequences therefore we should not do bad things. We may think that we can get away with it. However the universe doesn’t work like that. For very action there is a reaction, even if it may take some time. The laws of nature always work so that there is balance. Sooner or later, it will come back on us.
2) Doing good has its own reward and there are many advantage to not doing bad things. A few things to note is: agood conscience, being able to sleep, not having to hide from anyone, peace of mind, a good conscience.
3) We can avoid having to deal with a bad conscience and therefore we should avoid doing bad things. It is true that consciences have different sensitivities, not all work or work properly. However, if our conscience is hardened, something else will get us. If it is sensitive it can actually drive us crazy.
4) Justice finally catches up with us; this might be the natural justice
5) Somebody gets hurt. The universe is built on healing. It doesn’t like it when somebody hurts somebody. So it has to repair the damage.
6) God will not let us get away with anything bad that we may do and so there are good reasons to avoid doing bad things. God is the equalizer. Yes, some may delude themselves into believing that God does not exist. However, fact is fact and they will eventually have to answer to God, it might be sooner or it might be later but the day will come.
The conclusion of the matter after looking at all the angles is: do good things and avoid doing bad things. You will be happier and better for doing so!