The Governing Body of Jehovah's Witnesses believes they are God's channel of communication. They believe they are God's faithful and discreet slave. All other religions are thought to be dominated by Satan the Devil and these will all be destroyed at armageddon so that JW's can have their paradise earth. See the Watchtower Sept 1989
Another key doctrine of the Jehovah's Witnesses is that they have 'the truth'. When they talk they say they're 'in the truth'. Non believers are referred to as being 'out of the truth'. If anyone leaves the religion (and many do), these are called 'apostates' who have 'left the truth'.
Interestingly, some people who left the faith decades ago still say they 'left the truth'. Imagine the guilt and negative emotions that come to mind when people say they've 'left the truth' rather than they've left a religion they no longer agree with. Critics say the wordology of Jehovah's Witnesses is a form of mind control that keeps them firmly attached to the Watchtower religion years after they leave.
To non believers, the faith of Jehovah's Witnesses might be offensive. Many people who love God and have a close relationship with him are not Jehovah's Witnesses.
However Jehovah's Witnesses do not see that their faith could be offensive to outsiders. They believe they are loving and kind. They don't believe they are being critical of outsiders. They believe they are merely instruments of God who are delivering his message of 'truth'.
So it's a one way street. They feel hated and persecuted when someone says anything negative about their faith, but it's ok for them to say that only Jehovah's Witnesses have any scriptural hope of being saved because outsiders are dominated by Satan the Devil. They don't see anything wrong with this because according to their faith, they have 'the truth' and represent God.
Instead of accepting criticism as a way to improve their beliefs and become more Christ-like, they perceive that everyone outside of their faith is speaking out in anger or because they are controlled by God's enemy Satan.
JW's believe there are only two organizations in this world, - God's organization (their religion) and Satan's organization (non Jehovah's Witnesses). JW's who disagree are thought to be 'rebelling against God'.
You might be able to see from this belief system the reason why the faith of Jehovah's Witnesses is strengthened when they receive criticism. They believe that God's enemy (Satan) is tempting them to leave God and by standing firm like Job, Noah, and other faithful Bible characters, they will be blessed by him.
By being faithful to their religious leaders and completely trusting everything they say, they believe God will give them 'the prize' of everlasting life. See God's grace
In spite of their viewpoints about people outside of the organization, JW's are known for being peaceable and friendly towards everyone. See Friendship with a Jehovah's Witness.