R.C. Sproul writes:
When we break the law of God– something we do, have done, and continue to do–the problem is not simply that we have violated some moral, abstract standard that we call ‘law.’ The law of God is a personal matter. When we sin, we do not just sin against some abstract norm or piece of legislation. We sin against the one whose law it is. We do violence to him, to the Author of our very life. That is why sin is such an egregious matter in his sight — Commentary on Romans 4:13-23.
When we realize this truth, it helps us see the futility of saying that our sin isn’t sin (think adulterous relationships or oxymoronic gay marriage) because it doesn’t hurt anyone. Sin always is an affront to God and why we need to repent of it and look to Christ for salvation.