“And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.” (Genesis 6:5)
Many people believe that human beings are essentially good. Some Christians have even fallen into this line of thought. The appeal is obvious, but a faithful reading of the Scriptures doesn’t allow one to hold such a view.
As our passage (above) makes clear, the depravity of humanity was both deep and wide. The people of Noah’s day were totally depraved. It wasn't just that the bad outweighed the good, it was all bad (insofar as it was all man/flesh).
There is no good reason to think that the situation has changed since the flood. Without the grace of God, people are utterly sinful with no hope. We have no ability to recognize our sad state, no way to know God, and certainly no proneness to love and fear God.
Left to ourselves, we are literally left to self-worship. We share Satan’s self-will, but we go even further than he. We fall in love with the world. We become defined by the lust of the flesh, the lust of the eyes, and the pride of life.
The doctrine of original sin is a distinguishing one for Christianity. It is an essential doctrine. If it’s not true, we just need some help… but if it is true we need to humble ourselves and come to Christ (the only cure!)