The idea that God shouldn’t condemn behaviour he has built into humanity isn’t recent, and its flaws are pretty much dealt with in the opening pages of the Bible.
The idea that God shouldn’t judge natural behaviour operates on some shaky assumptions about the goodness of nature, that Catholic theologians have essentially supported. But the real answer to this dilemma comes from understanding just how big the effect of the fall was on human nature.
Here’s Calvin’s answer to the objection from hundreds of years ago. I’m reading the Institutes (again) for an assignment, and I’m wishing I’d read it before I wrote my ethics essay last semester because it’s good stuff.
“If any one thinks it absurd thus to condemn all the desires by which man is naturally affected, seeing they have been implanted by God the author of nature, we answer, that we by no means condemn those appetites which God so implanted in the mind of man at his first creation, that they cannot be eradicated without destroying human nature itself, but only the violent lawless movements which war with the order of God. But as, in consequence of the corruption of nature, all our faculties are so vitiated and corrupted, that a perpetual disorder and excess is apparent in all our actions, and as the appetites cannot be separated from this excess, we maintain that therefore they are vicious; or, to give the substance in fewer words, we hold that all human desires are evil, and we charge them with sin not in as far as they are natural, but because they are inordinate, and inordinate because nothing pure and upright can proceed from a corrupt and polluted nature.”
Calvin’s Institutes, 3.3.12