I'm not a KJV apologist, but these examples aren't that damning.
GENESIS 14. 18 But Melchisedech the king of Salem, bringing forth bread and wine, *for* he was the priest of the most high God...
GENESIS 14 18 And Melchizedek king of Salem brought forth bread and wine: *and* he was the priest of the most high God...
[KJV undermines the Mass and the eternal priesthood by changing "for" to "and" as if there was no connection]
You have to understand that the KJV is translated from Hebrew, not Latin. In Latin, it is unambiguously "for," but in Hebrew, the conjunction is waw
, which is typically translated "and," though it has a range of meanings in different contexts.
1 Tim. 4:14 14 Neglect not the grace that is in thee, which was given thee by prophesy, with imposition of the hands of the priesthood.
1 Tim. 4:14 Neglect not the gift that is in thee, which was given thee by prophecy, with the laying on of the hands of the presbytery.
Both Latin "gratia" and Greek "charisma" can be translated as either "gift" or "grace."
Luke 1:28 28 And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women.
Luke 1:28 And the angel came in unto her, and said, Hail, thou that art highly favoured, the Lord is with thee: blessed art thou among women.
I agree that the KJV and NAB translation is not adequate, but the Vulgate's "gratia plena" is not literal, though it captures the sense better.
Genesis 3:15 15 I will put enmities between thee and the woman, and thy seed and her seed: she shall crush thy head, and thou shalt lie in wait for her heel.
Genesis 3:15 15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.
[15 "She shall crush"... Ipsa, the woman; so divers of the fathers read this place, conformably to the Latin: others read it ipsum, viz., the seed. The sense is the same: for it is by her seed, Jesus Christ, that the woman crushes the serpent's head.]
Again, this is because the D-R is translating the Vulgate, which is alone among the ancient versions in having "she shall crush" (though there are some Patristic readings with this). The Hebrew, the Septuagint and the Syriac all say that the seed will crush.
2 Peter 1:10 Wherefore, brethren, labour the more, that by good works you may make sure your calling and election. For doing these things, you shall not sin at any time.
2 Peter 1:10 Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
[Substitution of "diligence" for "good works."]
I'm not entirely sure I see a huge difference here. The Greek verb is "spoudazo," which means to hasten, exert oneself, endeavor, give difference, etc. The Vulgate translation, while entirely correct, "colors" the phrase in a way that hides the nuances of the Greek word (in no way St. Jerome's fault - it's one of the chief limitations of translation).
Again, many of the discrepancies between the D-R and the KJV are due to the fact that they are not translating from the same source text. While some translation choices were undoubtedly affected by controversy, these examples, apart perhaps from Luke 1:28, are easily explained by the use of a different source text.