The term translated as share
describes the portion that is allotted to a particular person. Those who initially heard the reading of the book of Revelation were members of the seven churches. As Christians they had a share in the inheritance to come and would expect to receive their reward on the day of Christ’s return (Revelation 22:12). But here the Lord warns that doctoring his word in some way is to lose that share. This is plainly a serious warning to all Christians who hear (or read) God’s Word! Deleting or skipping over or ignoring, let alone reading material into the text, has eternal consequences; it leaves you outside
(Revelation 22:15).
19 and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book.