Revelation 1:6
Revelation 1:66who has made us to be a kingdom, priests to His God and Father—to Him be the glory and power forever and ever! Amen.
The Watchtower restricts ("he made us to be a kingdom, priests to his God and Father") to the 144,000 anointed Christians who will rule with Christ in heaven. The "great crowd" of other faithful sheep are not part of the new-covenant priesthood; they pass the Memorial emblems without partaking and approach God through the anointed class and the organisation it superintends.
Notice who "us" is. just said Jesus "loves us and set us free from our sins by means of his own blood" — that is every Christian, not a subset. So the "us" of v6 who are made a kingdom and priests is the same "us" — every believer Christ has freed. sharpens the point: "you bought people of every tribe and tongue and people and nation, and you made them to be a kingdom and priests" — exactly the language used of the great crowd in 7:9. The Watchtower divides what Revelation unites. The priesthood of all believers begins with Christ's blood, not with a 144,000-only ceiling.