I myself have reason for confidence in the flesh. . . . 5 circumcised on the eighth day, of the people of Israel, of the tribe of Benjamin, a Hebrew of Hebrews; as to the law, a Pharisee; 6 as to zeal, a persecutor of the church; as to righteousness, under the law blameless. --Phil 3:4-6
We ourselves were once foolish, disobedient, led astray, slaves to various passions and pleasures, passing our days in malice and envy, hated by others and hating one another. --Titus 3:3
What's fascinating is that the same man wrote both of the above statements, using the first person each time (the "we" in Titus 3:3 is placed emphatically). Paul could say: 'Look at my past--perfect!' as well as 'Look at my past--awful!'
Why? Doubtless in part because of the different audiences of each letter--Titus' ministry on out on the island of Crete (read: the backwoods of North Dakota) was probably much less influenced by Judaism; being more clearly gentile-oriented, Paul had little reason to speak of his Jewish past. But there is a deeper reason. One way in which we are "led astray, slaves to various passions and pleasures," is by stroking the pleasure of self-generated morality. Morality management is one of the deepest evils the human heart can know, and one of the dynamics that makes it so evil is that the person living this way thinks it is just the opposite, good.
Skeptical? Then note this: immediately after his statement in Titus 3:3, Paul goes on to deny that we are saved by the good things we do!
We ourselves were once foolish, disobedient, led astray, slaves to various passions and pleasures, passing our days in malice and envy, hated by others and hating one another. 4 But when the goodness and loving kindness of God our Savior appeared, 5 he saved us, not because of works done by us in righteousness, but according to his own mercy . . .
Paul doesn't note his and his readers' wickedness and then simply remind them that they are saved by grace. He notes their wickedness and then reminds them that they are not saved by the good they do--that to people famous for being devoid of good (Tit 1:12!). I conclude: there is a self-earning (gospel-defying) instinct in all people. Self-righteous morality is not one big step away from worldly wickedness; it is worldly wickedness.