Charles Ellicott Commentary Romans 5:13

"for until the law sin was in the world; but sin is not imputed when there is no law." — Romans 5:13 (ASV)

This much we can see; this much is a simple matter of history: that sin was in the world from Adam onward. But here is the difficulty. Sin existed, but why guilt? And why death, the punishment for guilt? Indeed, pre-Mosaic people sinned, but they could not rightly be condemned for their sin until there was a law to tell them plainly the distinction between right and wrong.

It should be noted that the law of nature (Romans 1:19–20; Romans 2:14–15) is not considered here. In the passages mentioned, St. Paul speaks of the law of nature only as applicable to his contemporaries or to comparatively recent times. He does not project its operation back into the primitive ages of the world; nor does he pronounce on the degree of responsibility that people, as moral agents, then incurred. This would align with the doctrine that the consciousness of right and wrong was gradually formed. Indeed, it is not to be said that St. Paul exactly anticipated the teachings of the inductive school of moralists, but there is much in their system, or at least in the results they seem to be reaching, that appears to align easily and harmoniously with the teaching of the Apostle.