We fight between good and bad. And then to strike a balance we say the two are relative. Some go even further to prove a point that we harbor both the devil and the angel.
Make a quick list of all the bad things we are not supposed to do as humans. Here is an attempt: Don’t hate others, Don’t kill others, Don’t envy, Don’t have extra marital affairs, Don’t overeat, Don’t lie and the list goes on. Fundamentally we as humans were all meant to do all of the above for survival. Kill, fight, have multiple partners (best mate with best genes), overeat just to mitigate the risk sleeping hungry tomorrow. We as humans have been doing all that for at-least 99.99999% of the time that we spent on this planet. That is millions and millions of years. But for the last two thousands years or so, we started believing in god and the inter-subjective reality of religion.
Religion essentially tells us to forget the past and suppress your natural instincts to do bad while giving you a half baked story of why you need to do good. Religion is telling us to forget the past for greater good. Being “bad” is all the set of behaviors which we all used to survive. So if bad is default then we must appreciate the fact that being good is acquiring new habits and behaviors for social acceptance.