Apparently you are not of a Christian persuasion. Man is fallen and left to his own devices will wander away from God. Most people left to their own devices are not decent. They are selfish and self centered. It is an external power that allows humans to become altruistic and interested in others.
Ah, you must be a protestant Insecure?
"The heart is deceitful above all things and desperately wicked. Who can know it?" (Jer. 17:9)