I've already posted this on another forum, but I thought I'd post it here too:
I think the existence of God is knowable through reason. I am interested in hearing what other people think of my argument for God's existence, especially people who disagree with me.
First of all, I don't really consider the concept of “religion” as a meaningful category. It's impossible to define. All ideas, including so-called religious and so-called scientific ones, are rooted in philosophy and philosophy is rooted in human reason. So the idea of God is a philosophical idea and must therefore be analyzed and debated through axiomatic logic.
Secondly, I'm defining “God” here in a broad philosophical sense: an Universal Mind that originated the rest of existence. It's not necessarily the God of the Bible or anything else. Although I'm a Christian, for the purposes of this argument, I'm only suggesting an infinite intelligence that caused the Universe.
It seems to me that the existence an infinite, universal creative intelligence can be deduced from the fact of existence. Even if I doubt all my senses, I know something exists, at the very least myself. I know that I exist as a conscious mind. So how does this extant world exist? There are only two possibilities: either it exists out of logical necessity or it is contingent upon something else that is logically necessary.
If I am contingent upon something else, it is likely that that thing is simpler than I am, since simple things tend to give rise to more complex things, meaning things with more composite parts. It is also more likely that a simple thing is logically necessary rather a more complex thing.
Now, it appears that the world outside myself is very complex. Assuming this world doesn't exist—that my mind has merely generated it—that means that my mind is very complex. So either way, the extant world is complex. So it's not likely to be logically necessary. Rather it's likely to be contingent upon something simpler than itself, something that is logically necessary.
This simple, logically necessary cause of the world is probably infinite. This is because infinity is the simplest possible thing: it has no composite parts, since the composite parts would themselves have to be finite.
Note that this contradicts of the more common idea that would say the most simple thing is pure nothingness. In fact, nothingness can not exist. We know this because nothing cannot cause something, and we know that something exists.
Thus, the basic, original absolute simplicity of reality is probably the opposite of Nothingness. It is an infinite All. As absolute All-ness, it has no boundaries or limits and is therefore infinite and infinitely simple.
Now, it is probable that this All-ness is intelligent. We know that intelligence exists, since we know, if we know anything, that we exist. And this All-ness, being All-ness, must embrace that intelligence. Therefore, it must itself possess intelligence. In fact, as the fullness of existence, it must be the fullness of intelligence. It must be a Universal Mind.