Robert Browning said, “Thought is the soul of the act.” Emerson said, “Thought is the seat of action. The ancestor of every action is thought.” If God destroyed the world once for its continually evil imaginations, is it not reasonable to believe that all of the sin, lust, and licentiousness that is rampant today grieves His heart just as it did in that day? Many people dream of sin, imagine sin, and—if granted the opportunity—would indulge in sin. All they lack is the occasion to sin. So, in the sight of God, they are sinners as great as though they actually had committed immorality. All transgressions begin with sinful thinking.
You who have come to Christ for a pure heart, guard against the pictures of lewdness and sensuality which Satan flashes upon the screen of your imagination, select with care the books you read, choose discerningly the kind of entertainment you attend, the kind of associates with whom you mingle, and the kind of environment in which you place yourself. You should no more allow sinful imaginations to accumulate in your mind and soul than you would let garbage collect in your living room.
I need my thoughts to be continually purified by the cleansing power of Your Spirit, almighty God. -Graham
"Good people" don't get to Heaven, only saved ones do. Are you saved from your sins by true faith in Jesus Christ?