Pope Shenouda III
Prayer is consecrating the lips and the thoughts and it is the sanctifying of the soul. Furthermore, it is reconciliation with God...
It is natural for the one who has a dispute between him and God, not to talk to Him. He does not pray. He does not have the intimacy to talk with God. If he starts to pray, it means that he wants to reconciliate with God... And if he prayed, he will be humbled by his talk with God and ashamed to defile his thoughts which were with God not so long ago. He will then reach modesty of the thoughts, which is a healthy, spiritual sign.
And so by praying, bad thoughts are abolished, as one continues to pray and uses prayer to enter into a spiritual atmosphere, far from the forces of darkness.