This has nothing to do with the fact that the KJV has the
added words in Romans 8:1; the discussion is not about doctrine.
Here is the NET footnote (with my emphasis):
The earliest and best witnesses of the Alexandrian and Western texts, as well as a few others (א* B D* F G 6 1506 1739 1881 co), have no additional words for v. 1. Later scribes (A D1 Ψ 81 365 629 vg) added the words μὴ κατὰ σάρκα περιπατοῦσιν (mē kata sarka peripatousin, “who do not walk according to the flesh”), while even later ones (א2 D2 33vid M) added ἀλλὰ κατὰ πνεῦμα (alla kata pneuma, “but [who do walk] according to the Spirit”).
Both the external evidence and the internal evidence are compelling for the shortest reading. The scribes were evidently motivated to add such qualifications (interpolated from
v. 4) to insulate Paul’s gospel from charges that it was characterized too much by grace. The KJV follows the longest reading found in M.
Furthermore, we can see umlauts (double dots) next to 1 John 5:7 in the Vaticanus manuscript. These umlauts appear next to other alterations. This lets us know that the Textus Receptus line of manuscripts would have predated the Vaticanus because it is recognizing a variant. So this tells us the Vaticanus is not the oldest that predates the TR for the KJV.
In addition, we see other similar verses in the same theme of teaching that are corrupted.
The part of Revelation 22:14 that says, "they that do his commandments" is altered.
Revelation 22:14 (KJB) says, "Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city."
Revelation 22:14 (ESV) "Blessed are those who wash their robes, so that they may have the right to the tree of life and that they may enter the city by the gates."
Two verses in certain Modern Bibles tell us that Jesus calls sinners (with no mention of repentance) while only one verse just says that Jesus calls sinners to repentance. This could lead us believe that Modern Bibles are telling us that Jesus will sometimes just call sinners with no repentance and other times He will call sinners to repentance.
Matthew 19:9 in the NAS1977, NAS95, NET, and NTFE says that one can divorce their wife for immorality instead of fornication (KJV). Meaning, the word “immorality” is ambiguous as to what kind of sin is being referred to here. So if one wanted to divorce their wife for lying, they could do so if they trusted these translations instead of the King James Bible.
Imagine the scenario:
Carlos: Pastor, I want to divorce my wife because she is lying. This agrees with the NAS95 you highly endorse in our church. It simply says, “immorality” is grounds for divorce.
Pastor: Well, I am not sure about that. I don’t think it would be wise to do so for that reason.
Carlos: But Pastor, do you not follow that Bible in what it says?
I remember one Christian on an online forum who really thought this was the best translation. The NAS95 has actually been proudly praised over the years by Modern scholars.
In short, it is a pattern of evidence.