Falcon: If they really were doing God's work and will, there would be satisfaction and merit to it all. Since it is just a manmade cult that is actually condemning people who buy into its message, it is a horrific delusion/waste of time, money, energy (cf. Mormon genealogical research and baptisms for the dead).
The same is not true of those who know and serve the Living God and even lay down their lives sharing the gospel. There is nothing more important than this and the reward will be great.
A false counterfeit does not disprove the genuine, so don't throw the baby out with the bathwater (Dawkins would assume all religion is idiotic and waste of time instead of seeing the great truth and benefit of the real thing).