After suffering yet another defeat at the hands of John Conor, the machines thought outside the box.
Upon discovering the true identity of John, which was Christian Bale, the machines formed a new battle plan.
By their logic, the rescue of Jesus Christ from the Roman empire would prevent the term "Christian" from ever coming into existence. and ergo, no Christians, no Christian Bale.
The Film Actors Guild was one step ahead of the machines though, they used the machines time-travel technology to send back their own answer, Roman-Bots.
Watch this epic struggle as the Roman-Bots attempt to prevent the future annihilation of the human race at the hands of the Christ-Bots, by ensuring that Jesus gets what's coming to him.