The sin nature is that aspect in humanity that makes us rebellious against God. When we speak of the sin nature, we refer to the fact that we have a natural inclination to sin; given the choice to do God’s will or our own, we will naturally choose to do our own thing.
Proof of the sin nature abounds. No one has to teach a child to lie or be selfish; rather, we go to great lengths to teach children to tell the truth and put others first. Sinful behavior comes naturally. The news is filled with tragic examples of mankind acting badly. Wherever people are, there is trouble. Charles Spurgeon said, “As the salt flavors every drop in the Atlantic, so does sin affect every atom of our nature. It is so sadly there, so abundantly there, that if you cannot detect it, you are deceived.”