The evidence is their own doctrines which contains false prophesying, false teaching and false preaching involving the preaching work of the Gospel of Jesus Christ by " His " instructions which differs from the Watchtower Corporation's.
It isn't the holy spirit of god directing this organization, its the sprit of men who were endeavored toward their power, control and money.
The men who started this organization were very much fear mongering theologically false prophet charlatans, full of their own sin and corruption.