(1) It teaches that Jesus is the head of man; that God is Jesus' head. (1 Corinthians 11:3) While it is appropriate for a woman to speak to a man or to God, Jehovah's Witnesses teach that she may not speak to Jesus. While a man may speak to a woman or to God, Jehovah's Witnesses teach that he may not speak to Jesus.
(2) It teaches that Jesus is our Eternal Father, Wonderful Counselor, Prince of Peace, and Mighty God, our savior, redeemer, High Priest, and King (Isaiah 9:6; Hebrews 5-7) However, Jehovah's Witnesses do not teach that Jesus is our Mighty God and teach that we may not speak to Jesus.
(3) It teaches that the only foundation which can be laid for Christianity is Christ and that the teachings on baptisms is part of that foundation, also that baptism corresponds to the ark which saved Noah and his family. (1 Corinthians 3; Hebrews 6; 1 Peter 3) But Jehovah's Witnesses teach that the organization is part of the foundation of Christianity, that the teachings on baptisms have changed, and that the organization corresponds to the ark. (Galatians 1:6-9)
What other things does the Bible really teach that Jehovah's Witnesses reject?