OK this needs to be cleared up.
Probability is the proportion of possible outcomes measured by the repeat exercise of a random event. A random event in this context is random sampling or random assignment.
Arguments about the probability of God's existence are nonsensical. Remember that probability is a measurement, and it is not the same thing as possibility.
So if we say that God has a 50% chance of existing then that make no sense at all. If God exist then God does not have a 50% chance to exist, as God already exist. If God does not exist then God does not have a 50% chance to exist, as God does not exist. So the argument makes no sense at all
Remember that it is possible outcomes; generally the debate is not about the outcome of God's existence, instead the debate is about whether or not God already exist.
Now you can say I am 50% confidant (the difference here is the 50% applies to your guess) that God exist, but since there are no empirical data, you are really just arbitrarily assigning a number to your guess of God's existence.
Just because someone assigns a chance or suggest there is a chance to one of their beliefs, that alone does not prove that belief is or could be true. Probability does not define existence, it is tool with limitations, and is only useful when applied within its proper context and support by empirical data and rational thought.