The aforementioned Keith DeRose discusses the "THE many" (Romans 5:18-19) issue here:
"The key difference, for our present purposes, between the translations is between the RSV’s “many” and the NIV’s “the many.”
To say that the many will be made righteous, while it doesn’t imply that all will be made righteous, neither does it imply, nor even suggest, that fewer than all will be.
In fact, v. 19, translated the NIV’s way, especially following on the heels of 18, seems to suggest, if anything, a positive answer to the question of whether all are covered, turning v. 19 from something that counts a bit against a universalist reading of v. 18 to a verse which, if anything, reinforces the universalist implications of v. 18.
My experts have informed me that the original Greek here is like the NIV, and unlike the RSV, in that there is not even a suggestion carried by 19 that fewer than all will be made righteous.
It’s no doubt in response to such considerations that the revision of the RSV, the NRSV, follows the NIV in using “the many” rather than “many.”
(But it was worth first presenting the RSV translation because many use English translations of the Bible, which, like the RSV, employ the inferior translation of this phrase.)" - Keith DeRose
Romans 5:19 RSV
For as by one man’s disobedience many were made sinners, so by one man’s obedience many will be made righteous.
Romans 5:19 NRSV
For just as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous.
