Spurgeon, "Ripe Fruit" #945. Micah 7:1

You are not mature if you have a high esteem
of yourself. He who boasts in himself is but a
babe in Christ, if indeed he be in Christ at all.

Young Christians may think much of themselves.

Growing Christians think themselves nothing.

Mature Christians know that they are less than nothing.

The more holy we are, the more we mourn our infirmities,
  and the humbler is our estimate of ourselves.

"Although I am less than the least of all
 God's people..."  Ephesians 3:8

"Christ Jesus came into the world to save
 sinners; of whom I am the worst." 1 Tim. 1:15