(1) Removing Jesus as mediator for all mankind by incorrectly saying that Moses was not the mediator for all mankind.
(2) Doctrinally prohibiting the worship of Jesus when the Bible shows that both people and angels do so.
(3) Holding secret tribunals to determine guilt, innocence, and/or the presence of repentance.
(4) Claiming that the Governing Body arose by the authority of the Faithful and Discreet Slave class.
(5) Adding requirements to those wishing to be baptized as Christians that the Bible does not require, including preaching which the Bible wouldn't even permit for an unbaptized person, and calling them teachings of the Bible.
None of these require anything beyond a Bible and their publications.