Hi,
This point has been made before but I think the very words the WT write which contradict the bible the quote make the point powerfully.
Have a read for yourself http://www.watchtower.org/e/jt/index.htm
Jesus told his disciples: "You will receive power when the holy spirit arrives upon you, and you will be witnesses of me both in Jerusalem and in all Judea and Samaria and to the most distant part of the earth."—Acts 1:8.
Hence, some 6,000,000 persons today who are telling the good news of Jehovah's Kingdom by Christ Jesus in over 230 lands feel that they properly refer to themselves as Jehovah's Witnesses.
Obviously six million people haven't read Acts 1:8 carefully enough!
All the best,
Stephen