Jehovah's Witnesses believe they have 'the truth'. When they refer to people outside their organization, they say they are 'out of the truth'. When they refer to Jehovah's Witnesses, they say they are 'in the truth'.
Other religions are referred to as 'Babylon the Great, the mother of the prostitutes and of the abominations of the earth.' Revelations 17:5, NIV. Watchtower June 15, 2008, article: Things From Which We Must Flee.
Even though they admit having no divine inspiration, they believe they are God's chosen people. Some JW's believe they are part of the 144,000 spiritual Israelites (or the 'anointed' ones). These believe they will go to heaven and rule over the entire earth. Most JW's believe they are part of the 'great crowd' or 'other sheep' who will live forever on a paradise earth ruled by Jesus and the 144000.
Every Christian believes they are chosen by God and Jehovah's Witnesses are no exception. The problem lies in this. JW's believe they are God's Channel of Communication. Everyone else is thought to be part of Satan's wicked organization. Who is Satan?
JW's believe they are the only ones who are chosen by God. Why? Because they believe they understand God and Jesus better than any other Christian church. They believe everyone else is taking the Bible out of context and has interpreted it incorrectly. They believe they have the truth and everyone else, ... the entire world and it's religious system is dominated by Satan the Devil. Watchtower May 1, 2009, articles: 'What We Learn From Jesus About 'the End' and 'Are We Living in "the Last Days"?
Jehovah's Witnesses notice that most Christians are not well versed in the Bible. They are not able to support from the Bible what they believe in. Jehovah's Witness on the other hand are well trained to defend their beliefs using the scriptures.
Because they know more about the Bible than the average Christian, they assume they have the truth, and everyone else has been deceived by their religious leaders who are part of this wicked world dominated by the Devil. When JW's go from door to door and see how little most Christians know about their faith, they come to believe they are chosen by God to preach the Good News of Jesus before armageddon strikes.
Jehovah's Witnesses believe they are chosen by God, and organized to do his will.