The Searcher:
"Ask them to explain the difference between 'upon' and 'over', and if they can think of a single example where both words could possibly mean the same thing.
Then refer them to the false translation of Revelation 5:10 in the NWT & RNWT, but also to the correct translation of the Greek in their Kingdom Interlinear Translation - which is reinforced by the diagram of the Greek words inside the front cover.
Ask them why a specific Greek word has been substituted with a different one in their translation?"
I believe one can make a case of wrong interpretation within the context of Scripture regarding the application of the preposition epi, but not on grammar grounds.
The preposition epi has variable meanings, including that of "over." The Shorter Lexicon of the Greek New Testament by Gingrich/Danker defines it: "With the genitive--1. of place, lit. and fig. on upon ...Before, in the presence of ... Over of power, authority, control Lk 12:42; Ac 6:3; Ro 9:5; Rv 5:10; 17:18."
Thus, it is not wise to use the Kingdom Interlinear against the New World Translation to determine the right or wrong translation of a preposition. A good interlinear like the KI just shows the basic meaning of a word, but the translation on the right, or any other for that matter, has more leeway in expressing the various nuances of a Greek word.