Here are a couple quotes from the WT on this:
WATCHTOWER BIBLE AND TRACT SOCIETY OF NEW YORK, INC.
117 ADAMS STREET BROOKLYN, NEW YORK 11201, U.S.A. PHONE (212) 625-1240
September 1, 1980
TO ALL CIRCUIT AND DISTRICT OVERSEERS
Page 2
Keep in mind that to be disfellowshiped, an apostate does not have to be a
promoter of apostate views. As mentioned in paragraph two, page 17 of the
August 1, 1980, Watchtower, "The word 'apostasy' comes from a Greek term
that means 'a standing away from,' 'a falling away, defection,' 'rebellion, abandonment.
Therefore, if a baptized Christian abandons the teachings of Jehovah, as presented by
the faithful and discreet slave, and persists in believing other doctrine despite Scriptural
reproof, then he is apostatizing. Extended, kindly efforts should be put forth to readjust
his thinking. However, if, after such extended efforts have been put forth to readjust
his thinking. he continues to believe the apostate ideas andrejects what he has been
provided through the 'slave class, then appropriate judicial action should be taken.
This is not to say that you or the elders should go on 'witch hunts,' as it
were, inquiring into the personal beliefs of your brothers. Rather, if
something reasonably substantial comes to the attention of the elders along
this line, it would be appropriate to make a kindly, discreet inquiry so as
to protect the flock. We cannot overemphasize the need to be cautious,
discreet and kindly as such situations are dealt with.--James 1:19, 20.
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"Apostasy."
"Persons who deliberately spread (stubbornly hold to and speak about)
teachings contrary to Bible truth as taught by Jehovah's Witnesses are
apostates." (Pay Attention to Yourselves and to All the Flock, 1991, p. 94)