Deceitful and desperately wicked!

(William S. Plumer, "Sinners Saved by Unmerited Kindness")

"The heart is deceitful above all things, and desperately wicked. Who really knows how bad it is?" Jeremiah 17:9

Man is the only creature on earth that practices self-deception. That we should sometimes deceive others is proof of our depravity; but that we should spend our lives in self-deception is truly astonishing! Men of the fewest virtues commonly have the highest thoughts of themselves. How strange and yet how common that he, whose heart has deceived him a thousand times, should yet confide in it as if it had always been honest!

The human heart deceives every being but one — and it would deceive Him, if He were not omniscient. None but God knows all the depths of iniquity and duplicity within us.

Though the language of the Bible is strong, it is just. God declares, and every Christian knows by sad experience — that his heart is deceitful above all things. A perfect knowledge of the treachery of our hearts is possessed by none but God.

The heart is also VILE. It is "desperately wicked."

It loves vanity, and folly, and sin.
It hates holiness, and truth, and divine restraints.

The heart is . . .
  a sink of iniquity,
  a pool of pestilential waters,
  a cage of unclean birds,
  a sepulcher full of dead men's bones.
It is torn by wild, fierce, unhallowed passions.
It rejects good and chooses evil.
It is wholly corrupt.
It is full of evil.
There is no soundness in it.

"For from the heart come evil thoughts, murder, adultery, all other sexual immorality, theft, lying, and slander! These are the things which defile the man." Matthew 15:19, 20

"He who trusts in his own heart is a fool!" Proverbs 28:26