They assume such things as "the probability of God's existance is 1 in 2." As in He either exists or He doesn't. But that's not the case - Either He exists, or Zeus exists, or there is no God, or there are many gods, or an infinite amount of other possibilities that are equally likely.
The probability for an either/or question like this is 50/50. He exists or does not.
Then, you can calculate what type of God exists, and get into what you are talking about.