To those who by persistence in doing good seek glory, honor and immortality, he will give eternal life. But for those who are self-seeking and who reject the truth and follow evil, there will be wrath and anger. Sin is a selfish attitude in our heart. Self-seeking means we are concerned for ourselves more than others. Our own interests are our chief concern.
Sin begins with being selfish in our heart and results in disobedience in our behavior.
We all inherit a sin nature from Adam. Surely I was sinful at birth, sinful from the time my mother conceived me. Even though we have done nothing right or wrong at this point, we are still sinners in the sense that we are dead spiritually and separated from God. This condition was passed down to us from Adam. As a result, we are subject to the consequences of sin which include suffering and death.