KINGS AND PRIESTS
the correct text and translation is as follows, and read on from the last expression: "And made (not hath made) us (Tregelles read (...) (heemin) for us) a kingdom, (all read (...) (basileian) a kingdom; instead of (...) (basileis kai) kings and) priests to his God and Father (or priests to God, even His Father)."
we have the same expression in chap. v.10, where the Greek Text has to be corrected in a similar manner.
There the alteration of the text has been the parent of all the wrong translations made of it.
It is the song, the new song, sung by the four living creatures, and the twenty-four elders. 
They say (ver.9): "Worthy art thou to take the book, and to open its seals; because thou wast slain and madest a purchase for God (the word "us" must be omitted according to Lachmann, Tischendorf, Alford, Westcott and Hort, and R.V. There is an Ellipsis. The R.V., having taken out "us," has supplied "men" in italics. We may supply "a People," or translate as we have done. All the Texts agree in altering the pronouns that follow in this and the next verse. This necessitates the omission of "us" here. If one is changed, all must be changed for the sake of consistency and sense. But this entirely does away with the supposition that these heavenly beings were themselves redeemed, or were the subject of their own song (See below, on chap. v.9) by thy blood (a purchase, namely) out of every tribe, and tongue, and people, and nation, and didst make them (so all the Texts and oldest MSS.) to our God (Alford omits these words) a kingdom (so all the Texts and best MSS.) and priests, and they shall reign (so all the Texts and oldest MSS.) over the earth" (see further on chap. v.9,10 below).
Here we have again the expression "a kingdom and priests." While we have not a word like this in the Church Epistles, yet we have a passage in the Old Testament where very similar words are used, and truth declared of Israel. Exodus 19:5,6: "Ye shall be a peculiar treasure unto me above all people: for all the earth is mine: and ye shall be unto me a kingdom of priests, and an holy nation."
True, these words are found in the New Testament; but they are in the Epistle addressed to the sojourners of the Diaspora"  : i.e., "the Dispersion," a believing remnant of scattered Israel. These are the People who are concerned in the promise of Exodus 19:5,6, and Revelation 1:6 and v.10: and not the Church of God.
 The number four and multiple of four (4X6) marks these and their song as pertaining to the earth and to man as such, not the Church.  (...), scattered abroad, came to be the technical term for the dispersed portion of Israel. It is found in LXX. Jeremiah 34.(Sept. xli.) 17. Psalm 147:2 (Sept. cxlvi. 2). Judith v. 19. Compare Josephus, Wars, 7. 3. In the New Testament we have the word in John 7:35. James 1:1. 1 Pet. i. 1. (We may compare the technical use, in Holland, of the term "The Beggars").
 (...), scattered abroad, came to be the technical term for the dispersed portion of Israel. It is found in LXX. Jeremiah 34.(Sept. xli.) 17. Psalm 147:2 (Sept. cxlvi. 2). Judith v. 19. Compare Josephus, Wars, 7. 3. In the New Testament we have the word in John 7:35. James 1:1. 1 Pet. i. 1. (We may compare the technical use, in Holland, of the term "The Beggars").