The impulses are not sin, in the sense of something moral, or legal. They are not of themselves transgressions, nor do they alienate us from God in any moral sense. But they cannot be separated from sin. They are the root of sin, called in the scriptures "sin in the flesh". They are related to sin, as the root of a plant is related to its fruit. Sin had to be in the flesh of Jesus, in order for it to be condemned there. Therefore, the impulses themselves had to be sin, in the physical sense. Bre. Stone and Hensley deny this aspect of sin. The apostle Paul says "whatsoever is not of faith is sin." (Rom 14:23) The impulses are of the flesh, not of faith. The impulses therefore, are sin, though they are not transgressions, and they are not held against us in any meaningful way. But as sin, they required the perfect sacrifice for redemption, and also as the key to demonstrating what is due to sin.