Words in the New World Translation's main text that have no corresponding word in the Greek, at points that affect who Jesus is. Strongest first.
The additions
Colossians 1:16-17, 20: "all other things" ● Documented
Added word: "other," five times
Greek (1:16). hoti en autō ektisthē ta panta, ὅτι ἐν αὐτῷ ἐκτίσθη τὰ πάντα: "because in Him were created all things." No word for "other" (such as alla or loipa) appears. checked
NWT (2013). "because by means of him all other things were created in the heavens and on the earth... All other things have been created through him and for him." Verse 17: "he is before all other things, and by means of him all other things were made to exist." Verse 20: "to reconcile to himself all other things." checked
LSB. "For in Him all things were created, both in the heavens and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things have been created through Him and for Him." checked
What the addition does. Without "other," the Son creates all created things and so stands outside creation. With "other," He becomes one created thing who made the rest, which is the Watchtower's teaching.
The bracket history. The 1984 Reference edition printed "all [other] things" in brackets, five times, with the footnote "'All [other],' as in Lu 11:41, 42." The 2013 revision dropped the brackets. checked
Say it. "Your own 1984 Bible put 'other' in brackets because it isn't in the Greek. Why does the 2013 edition hide that?"
Philippians 2:9: "every other name" ● Documented
Added word: "other"
Greek. to onoma to hyper pan onoma, τὸ ὄνομα τὸ ὑπὲρ πᾶν ὄνομα: "the name that is above every name." checked
NWT (2013). "the name that is above every other name." Reference edition (1984). "above every [other] name." checked
What the addition does. "Every name" includes the divine name; "every other name" leaves it out, keeping Jesus's name below Jehovah's. Verses 10-11 then apply Isaiah 45:23, where every knee bows to Jehovah, to Jesus.
"Jehovah" 237 times in the New Testament ● Documented
Added word: the divine name, where the Greek manuscripts have "Lord" (Kyrios) or "God"
NWT appendix. The translation "uses the name Jehovah a total of 237 times in the Christian Greek Scriptures." It concedes that the surviving Greek copies read Kyrios, and argues the name was in the originals and later replaced. checked
What the addition does. It decides, verse by verse, which "Lord" is Jehovah and which is Jesus. In passages that apply Old Testament Jehovah texts to Jesus, that choice removes the identification.
Their answer. They argue from Hebrew copies, early Septuagint fragments and "Hallelujah" in Revelation that the name was originally there. Grant that this is their argument; the point is that it is a reconstruction, not a reading from any Greek New Testament manuscript.
Acts 20:28: "his own Son" ○ Debated
Added word: "Son"
Greek. tēn ekklēsian tou theou, hēn periepoiēsato dia tou haimatos tou idiou: "the church of God, which He purchased with the blood of His own" (or "with His own blood").
NWT (2013). "to shepherd the congregation of God, which he purchased with the blood of his own Son." Reference edition (1984). "the blood of his own [Son]," in brackets, with an appendix discussion. checked
What the addition does. Without "Son," God purchased the church "with His own blood," which only works if Jesus is God.
Use with care. Some respected translations, such as the NRSV, also supply "Son" here, because tou idiou can mean "His own one." The fair point is the dropped brackets, not the word itself.
Titus 2:13 and 2 Peter 1:1: "and of our Savior," "and the Savior" ● Documented
Added words: a second "of" (Titus); a second "the" (2 Peter)
Greek. Titus 2:13: tou megalou theou kai sōtēros hēmōn Iēsou Christou. 2 Peter 1:1: tou theou hēmōn kai sōtēros Iēsou Christou. Each has one article governing both nouns: "our great God and Savior, Jesus Christ"; "our God and Savior Jesus Christ."
NWT (2013). Titus 2:13: "the great God and of our Savior, Jesus Christ." 2 Peter 1:1: "of our God and the Savior Jesus Christ." checked
What the addition does. The supplied "of" and "the" split one person into two, so "God" and "Savior" no longer both describe Jesus.
Support it. 2 Peter uses the identical construction for Jesus alone: "our Lord and Savior Jesus Christ" (1:11; 3:18). If that is one person, so is 1:1.
John 1:1: "the Word was a god" ○ Debated
Supplied word: "a"
Greek. kai theos ēn ho logos, καὶ θεὸς ἦν ὁ λόγος. Greek has no indefinite article, so "a" is the translator's choice.
NWT. "In the beginning was the Word, and the Word was with God, and the Word was a god." LSB. "In the beginning was the Word, and the Word was with God, and the Word was God." checked
What the addition does, as your notes put it, is lead to one of two places. One is polytheism: two gods, the God and a god, with salvation resting on the second. The other is Arianism: Jesus as a created, lesser being.
Why it's rated Debated. English routinely supplies "a" where Greek has no article, so the Witness will say every translation does this. Win it on consistency (The broken rule) and on grammar: their own study note calls this theos "qualitative," which describes the Word's nature.
One correction to the notes. Arianism was answered by Athanasius and the Council of Nicaea in 325. Irenaeus died about 202, roughly a century before Arius, so he didn't refute Arianism itself, though he wrote against earlier errors about Christ.
Revelation 22:18-19, used fairly
LSB. "I bear witness to everyone who hears the words of the prophecy of this book: If anyone adds to them, God will add to him the plagues which are written in this book. And if anyone takes away from the words of the book of this prophecy, God will take away his part from the tree of life and from the holy city, which are written in this book." checked
How to use it. The warning is about changing the message of Revelation. Every translation supplies some words, so don't apply it to a supplied "a" or "both." Apply the principle where it fits: words that change what the text teaches about God, added without marking. Deuteronomy 4:2 and Proverbs 30:6 make the same point for all of Scripture.
Don't say "Every Witness is cursed under Revelation 22." It's an overclaim, it ends the conversation, and your own Bible has italics.