They know about 50 or so isolated verses of the Bible as prooftexts. Most of this is out of context.
What they believe is mandated by the Governing Body and they cannot variate for this, or else they will be disfellowshiped for apostasy and shunned by friends and family. And since they are not supposed to make friendships with non-JWs (the world), that means losing everyone they know. If you continue down this path, they will slowly encourage you to distance yourself from any friends you have.
Anyway, the Governing Body teaches that they are the Faithful and Discreet Slave on Matthew 24:45, the sole channel appointed by Jesus to give "spiritual food". One's spiritual health and relationship with God is dependent on recognizing them as the Faithful Slave. Christ is said to appointed this Faithful Slave in the year 1919, a few years after his invisible Presence began in 1914.
If you don't believe any of this, you will be destroyed for all eternity at Armagedom.
What do you think about their beliefs now?