As human beings, we are all prone to overestimating our own goodness and abilities. We tend to rely on the goodness of our hearts to guide us through life and to hopefully make sound judgements. But God has something else to say about our goodness. In Jeremiah 17:9, it says that the heart is deceitful above all things, and is desperately wicked, and that no one knows it. The scripture in Mark 7:21-23 even says "For from within, out of the heart of man, come evil thoughts, sexual immorality, theft, murder, adultery, coveting, wickedness, deceit, sensuality, envy, slander, pride, foolishness. All these evil things come from within, and they defile a person."