Here is what the Pharisee says: “God, I thank Thee that I am not as other men are.” He is not, in fact, thanking God for this, acknowledging that it is God’s doing that he is not as other men. No; the words: “God, I thank Thee … ” are nothing more than an exclamation, a flattering approach to God so that God will listen to his boast. For, from all that he says, he is not thanking God for anything; on the contrary, he is blaspheming against God by blaspheming against the rest of God’s creation. He is thanking God for nothing; everything that he says about himself is expressed as his own doing, achieved without God’s help. He will not say that he is not an extortioner, an unjust man, an adulterer or a tax-collector because God has preserved him from this by His power and His mercy. In no way; but only because he is what he is in his own assessment: a man of such exceptional type and worth that he has no peer in the whole world.
“Wherever God is — there is peace. And the opposite is self-evident: where there is envy, enmity, impatience, self-love — there is the devil. Wherever the devil is — there, everything is ruinous, proud and hostile.”
“We hear it frequently remarked that it matters not what one believes if he does right. But if one does not believe right, he does not do the right thing—that is, if his belief is sincere and carried out in practice. If one believes that which is wrong, and still acts otherwise from force of circumstance, he is wrong in heart. A man may believe in polygamy, but the law and common custom may forbid its practice. He would be in outward life aright, but in heart would be a virtual polygamist. And if circumstances were favorable, his life would bear its legitimate fruit. And this is just as true of every other moral evil. It is all-important to believe right. Every false religion which has cursed mankind has started in a wrong belief. It might not have affected practical duties for a time, but the fruit finally developed. Thus belief in that first lie of Satan’s (Gen. iii: 4) has borne its legitimate fruit in—first, the deification of the beautiful, and unnatural curiosity; second, self-love, delusion, and idol-worship; third, free-thinking, protesting, infidelity, and anarchy.”
“Firmly purpose in your soul to hate every sin of thought, word, and deed, and when you are tempted to sin resist it valiantly and with a feeling of hatred for it; only beware lest your hatred should turn against the person of your brother who gave occasion for the sin. Hate the sin with all your heart, but pity your brother; instruct him, and pray for him to the Almighty, Who sees all of us and tries our hearts and innermost parts. ‘Ye have not yet resisted unto blood, striving against sin.’ (Hebrews 12:4) It is impossible not to often fall into sin unless you have a hatred of it implanted in your heart. Self-love must be eradicated. Every sin comes from the love of self. Sin always appears, or feigns to be, to wish us well, promising us plenteousness and ease. ‘The tree was good for food, and it was pleasant to the eyes, and a tree to be desired to make one wise.’ (Genesis 3:6) This is how sin always appears to us.”
To deny oneself means to give up one’s bad habits; to root out of the heart all that ties us to the world; not to cherish bad thoughts or desires; to suppress every evil thought; not to desire to do anything out of self love, but to do everything out of love for God.