It means that many honorable and religious people (who carry the ego of sorcery within) with good intentions have unconsciously altered the bible. This is why we must always meditate on everything we read in order to take the divine content from it and discard the rest.
Weep not: behold, the Lion of the tribe of Judah,
the Root of David, has prevailed to open the book,
and to loose the seven seals thereof. - Revelation 5: 5