Theists - how certain are you that a God exists?

[robvalue]

In case it's not obvious, here are some examples of why defining something does not make that thing even possible, let alone existent:

X is the smaller number greater than zero.

X is the single solution to the equation x^2 = 4.

X is the first whole number that is higher than 5 but lower than 3.

Mike is a man who is 78 feet tall and eats bowling balls for breakfast. He can also rewind time. Gravity does not apply to Mike.

Now, the last one in the list is the only one that could be possible. But that surely doesn't mean it is possible, and everything we've ever experienced would lead us to conclude that it is incredibly unlikely to be possible. The other three are simply impossible, even though I've defined them.

If you define something, it's up to you to demonstrate why it is reasonable to believe that you're referring to a non-empty set.