In order to understand our human nature we must first understand evil. Evil is the violation of, or intent to violate, some moral code. Definitions of evil vary, however, evil is commonly associated with conscious and deliberate wrongdoing.
Many present day philosophies and worldviews claim the people are basically good and that bad behavior is the exception. The Bible states the opposite - people are selfish and sinful. Because of this, people need a Savior in order to be acceptable to God.
According to the Bible Jesus said that, "Only God is good," meaning He is the only One who is inherently good which infers that we are not. God gave us the gift of free will. With that free will our first mother and father decided to sin and we as humans inherited the fallen natures of Adam and Eve. Romans 5:12 states “So then, just as sin entered the world through one man and death through sin, and so death spread to all people because all sinned.” In Ps 51:5, David says, Look, I was guilty of sin from birth, a sinner the moment my mother conceived me. (NET) According to the bible from the time we were conceived we were in sin. Ephesians 2:3 also establishes this, saying that we are all "by nature children of wrath." If we are all "by nature children of wrath," it can only be because we are all by nature sinners-- Rom 3:23 says that all have sinned and fall short of the glory of God” If we were in fact created good, then why would god send his only son, Jesus to die for our sin and save us?
Other than the bible the Quran states, “The mind of man is ever ready to incite to evil” Inferring man is more evil than good. Two of the worlds largest belief systems claiming