Why is the wrong question.

How is the right one.

Why is a human construct. It doesn't have to have an answer.

But since this is what's being asked the answer is: There is no reason. Existence is what you want to do with it. It's a consequence of quantum reactions at the end of the day. If i must have a reason, it's the pursuit of Happyness.

And yes, i know that it's cruel that it is this way and people turn to Religion because of it, but that is weakness. It's refusal to accept reality and fall for fairy tales.

Oh, to answer some of the questions:

Our thoughts are electro-magnetic pulses through brain cells. In truth they may very well be the product of chemical interactions and we actually don't have any free will at all. Though, we do seem to have the ability to resist it... or do we? It may just be adaptation skills.

Others being real. Well... yeah, it can be a huge illusion, but we can safely say they are real in a non-scientific way by unpredictability. When someone talks to me about a topic i never heard before, i don't think my mind could have locked it away just for that precise moment. If it is, then daaamn, our brains would be devious and highly efficient to say the least. I don't believe my brain can do all that or i'd be a super intelligent amazing being (way more than i already am :D ).

After death... who knows? It's most likely the end of consciouness. But the atoms that compose us will live on and continue to be star dust. The universe is much much bigger than any of us. We are but a spec of dust in the wind.

I guess existance is not the weird thing. Because we are atoms, we existed before. Counciousness is the odd one... or illusion of?

Yeah, we are nothing basically. Just live your lives to the max. Find happyness. That's what life is about.

Thoughts and electro-magnetic pulses are not the same thing, they are two very different things with very different sets of properties. The two are related, no doubt, but their relationship is not one of identity.

Whether or not free will exists depends on how it's defined. If by "free will" you mean the ability to make decisions completely unaffected by the circumstances surrounding us then you're absolutely correct that it doesn't exist, and this is the case even if our thoughts AREN'T the product of chemical processes. If by "free will" you means the capacity to make our own decisions, the you're absolutely wrong and free will does exist, even if we assume physicalism to be true and our thoughts to be the product of chemical processes in our brains. If physicalism is true then we ARE our brains and the processes taking place in them, so saying that they're the ones responsible for our choices is the same as saying that WE are the ones responsible for our choices.

If there is no consciousness then what is the thing being made to believe that there is a consciousness? Consciousness can't be an illusion because only conscious beings are subject to illusions.

God is a seahorse. 

Sure, it's reasonable to assume there's a cause.

I've never actually heard a real person say this. But I do hear "Just because you can't see it doesn't mean it doesn't exist" or something to that effect.

We know this because of our understanding of planes. We designed them and have tons of data on the issue. Same can't be said for deities. 

Nothing can be infinite.

The reason is simple, say the universe (or anything for that matter) is infinite, but then it expands by whatever margin, then it would be suddenly bigger than infinite. So therefor all things are finite. It seems to us like it's infinite because it's to big for us to comprehend. Of course it can grow, which just means it's bigger than it was (obviously :)), but still it's finite.

... that's not how math works.

2 things:

- There are, in fact, different , much bigger infinites (this is irrelevant in this case, though)

- "expansion" simply means that any 2 elements have, at limit, a greater distance between each other. This is fully possible, while staying within the same infinite subset of any metric.

Also, an infinite number of possibilities does not mean every single possibility, since if it's infinite there obviously can't ever be everything. But as for the universe being infinite, is there undeniable proof that it is?

No, we officially have no clue what is beyond the observable universe, because, well... It's not observable (as the edge" of the observable universe is parting at speed of light) For all intents and purpose, it does *not* exist, from our perspective, as there is no way to interact with anything outside of the observable universe (because, again, it's expanding at speed of light.)

I mean, what would the "nonexistence of the universe beyond ..." even be defined as? Mathematically, you can feel free to define your space however you like. Physically, again... no interaction. Your choice to say if any supposed entity with no interaction whatsoever with our point element "exists" or not.

I was not talking about math. In math infinity is abstraction, it's a concept, it's not 'real' because it can never be obtained, otherwise it would not be infinite.
In terms of physics (applying to our reality) nothing can be infinite. It doesn't mean you can't use infinity in physics for calculations, but it's just used in case a theory is insufficient to give a proper solution to a problem.

Nobody can really explain to you what is existence.

The first thing you need to think of is who are you.
Do you believe you are your physical body, and that your consciousness is a 'product' of your brain?
Or do you believe you are the consciousness and that the physical body is a 'tool' for you to experience this reality?

When you are with the first group, then your existence is just coincidence, a by product of this universe with probably no real purpose.
If you belong with the second group, it's hard to answer how your consciousness came to be, but there is probably a reason why you are excisting in this reality. To learn, to experience and to grow your consciouness for a next stage/life (or however you want to name it).

It's not important which you believe is true, but understanding to which camp you belong will maybe help you to find a satisfying answer :)