You can weed-whack a field infested with Canadian thistle, but the seeds are so deeply embedded throughout the soil that the weeds will keep sprouting up until some radical treatment of the soil takes place.
A pernicious aspect of the nature of sin is how it convinces us that we can separate sinful acts from the sinful desires which gave rise to the acts. Modern gurus of morality can see the prickly weeds of sinful acts. But they are blind to the seeds hidden deep in the soil that continually give rise to those weeds. They think they can eradicate the one, while remaining ignorant of the other.
But Jesus, of course, taught that the sinful acts of murder, adultery, vigilante justice, or broken vows arise from sinful hearts (Cf. Mt. 5:21-48). You can attempt to legislate away sinful acts, but you’ll never legislate or medicate away sinful desires.
Without Christ, the soil of the human heart is littered with seeds of ungodly desires waiting to spring forth in vibrant evil. Another way to put this is that sin is in the second look. It’s no sin to see your neighbor’s wife, property, or prestige. What is the sin is the second look. The lustful gawk. The seething stare. The envious spying. The greedy glare. The acts of rape, murder, theft, or lying all arise from these seeds of desire.
Sinful man thinks he can mitigate the most stark acts of sin by passing laws, or by medicating the populace, or by introducing some revolutionary curriculum to Kindergartners. This is just lopping off the most thorny weed, and doesn’t deal with the seed infested soil. The message of Christ, which we proclaim, is that You need an entirely new bed of soil. You need a new heart.
Our nation has cherished and fostered all manner of sinful desires, and yet we remain aghast when the vileness and the horror of those deformed desires come into full bloom. The second look of sin belies a deep discontentment, a profound brokenness within our culture. Instead of receiving God’s blessings with gratitude, the depraved heart prowls around looking for unlawful pleasures.
As the saints of God, we know that we are rebegotten. We’ve been given new hearts. Yet, still we allow the seeds of selfishness, lust, pride, and envy to light upon the soil of our hearts. This requires grace to be vigilant, that we might faithfully root up such desires when first the Spirit convicts us of taking a second look at the things that are not lawful for us to have. Do not nurture even the smallest weed of sinful desire.