From an article in The Catholic Weekly:
Watchtower law states: “Most firmly hold, and in no way doubt, that every apostate or dissenter is to be destroyed at Armageddon, unless before the end of his life he repents, and restored to the Christian Congregation of Jehovah's Witnesses.”
And up to this day the elders' oath of allegiance of to the Governing Body states: “With all our power we will persecute and make war upon apostates and dissenters.”
Thus militant intolerance is built into Watchtower thinking.
But justifying this attitude, the authoritarian Governing Body states: “Being the guardian of revealed truth, faith and morals, we cannot tolerate the spreading of any teaching that is harmful to the faith of the faithful.”
(See citation below...)