Their religion is a cult, a perversion of Christianity. They believe that Jesus Christ was a created being, an archangel, not the Son of God.
Like all cults, their authority rests on an, "AND," that is, the Bible AND the writings of their founder, Russell.
They believe that their "Good Works," (knocking on doors) will earn them brownie points with God, and pay off their bill in part for sin.
Even if you don't subscribe to Christianity, don't mistake these people for Christians. They are not.