Mock dialogue of the Theist/Atheist discussion here.

[Jenny A]

What if you perceive you yourself have an objective value but don't know how to measure it? Why is that impossible rationally?

To give an example, I see the moon. I know it has a mass. I don't know how to measure it but I know it has a weight. 

Why can't the same be true about the perception of myself?

The physical effects of the moon are quantifiable. If we do measure it, we will reach the same conclusions about it's mass. We both know it has mass and that that mass is quantifiable. If we pretend it doesn't exist, it won't go away. It will still reflect the sun's light. It will still affect earth'so orbit. In short it exists.

Harry Potter exists in our thoughts. But we don’t all have the same picture of him, and we can't weigh him. Unlike the moon, if we all cease to think about him, he will cease to exist. God exists in exactly the same way as Harry Potter, no more, no less. That is to say they are both thought constructs nothing more.