You must come to see that it is possible for a man to be self-centered in his self-denial and self-righteous in his self-sacrifice. He may be generous in order to feed his ego and pious in order to feed his pride. Man has the tragic capacity to relegate a heightening virtue to a tragic vice. Without love benevolence becomes egotism, and martyrdom becomes spiritual pride.
Martin Luther King, Jr., “Paul’s Letter to American Christians,” sermon delivered at Dexter Avenue Baptist Church. The entire text is available (PDF) through Stanford’s MLK Papers Project.