Prayers for cleansing are useless when we continually and knowingly let images into our heart that are so opposite from the cleansing we say we crave. Self-discipline is as much a part of our purity as prayers for it are. Never let yourself dwell on things that are going to be problematic to a life of holiness. We need to pray to be clean, but we also need to be intentional about things that we do not want to enter our heart and mind.
“Watch over your heart with all diligence, For from it flow the springs of life.” Proverbs 4:23 (NASB)
