IF there is a supreme being in the form of a GOD...how could we know it?

Look and see how the world is. Ask the main questions though. Are we perfect? Are we in the state of being idyllic. Um, no we're not. So there's your answer.

Observe because there really isn't. If there was a God you'd think it'd be that complicated. No it wouldn't, obviously.

If an omnipotent benevolent god had created us and wanted us to know so, it could simply have us born with the knowledge of its existence, and what, if anything, it wants from us.

This does not affect free will, because:

1) Even people who are 100 percent sure of their religion (the vast majority of people who have ever lived) still commit what their religion considers sins

2) The deity could still give us free will anyway, otherwise it wouldn't be omnipotent

It would not use humans as prophets to get its message out, since clearly that channel of communication results in contradictory messages, and cannot be distinguished from messages that are not from the deity but only from the prophet (lies and insanity). The fact that there are many contradictory religions proves this beyond doubt.

From this reasoning, I conclude that either

a) we were not created by a deity at all, or

b) we were created by one that is not omnipotent, omniscient, and/or benevolent, or

c) we were created by a deity that doesn’t care if we know it created us and has no demands of us.

I believe a) is correct.

I figure that a god that was capable of creating us would also be able to communicate with us.

He has chosen not to do so for some reason, most likely because he doesn't exist.

It is in print.  Hebrews chapter 1.

Ants haven't landed a robot spacecraft on Mars, but humans are intelligent enough to understand a god -- if the god isn't inept at communicating.

If there is a God, he is CLEARLY inept.

Let’s put it this way:  if there was a god, we would not still be debating it 2000 years later. 

Just look for a burning bush, whilst on ecstasy, I’m sure you’ll do fine