Although there are many variants, the main trunk (of which most of the others are variants) can be summarized as the belief that a quasi-divine entity, who was briefly present on the earth in human form but was killed and then magically revived in non-human form, allows people to live happily forever in the form of a spirit if they eat crackers and wine which have been magically transformed into his flesh and blood (but only in essence; you can't actually tell the difference from regular crackers and wine) and telepathically accept him as their master. He allows people to live forever by removing an evil force from their souls which the creator of the universe put into all humans because a talking snake convinced a rib-woman to eat from a magical tree.
People who do not accept this entity as their master (or, in some cases, are insufficiently fervent in their acceptance of his mastery) are either condemned to an eternity of torment (typically involving fire) or else are merely prohibited from living happily ever after (entering "heaven").
Due to the fact of Christianity's central figure (Jesus Christ) being essentially a revived corpse, as well as the emphasis on eating the flesh and blood of this corpse, Christianity is sometimes colorfully described as a zombie death-cult. It is not clear if Christ actually qualifies as a "zombie", however, since it is his flesh which is being eaten rather than him trying to eat other people's brains. It's not clear whether Christ has a will of his own, which would also disqualify him as a zombie, or if he is purely an agent of God's will (which arguably would mean that God is Christ's bokor [W] if Christ did fit the definition of zombie).
Thanks to Bay of Fundie for inspiring the summary of Christian belief.