The Big Bang is evidence for the existence of the supernatural

[Welsh cake]

Nope, its not. Since the universe most probably had a absolute beginning, it must have had a cause.

The problem here is causality and that you're arguing that god doesn't require a cause (you're a fan of Aristotle's work I take it?) which is special pleading bull-crap. You arrive at the conclusion the universe requires a cause through inductive reasoning, however though causality applies from our experience on Earth via observing the known cosmos it does not necessarily apply to the universe in its entirety. We don't know exactly how the current universe as we know it today formed; while that doesn't stop discussion it does however prevent us from asserting anything and leaves everything else open to speculation as we enter into the realm of theoretical physics; we've no concrete evidence only various theories (Big Bang) and other appealing hypothesises. We do know a good deal regarding the laws of thermodynamics in that matter and energy can't be created or destroyed, merely changed which would suggest they may possibly be eternal, as unfathomable as that may be to you. You've not even glanced at string theory or other studies within cosmology and fallen headlong into the trap of making invalid causal loops and chains.

God however dwells in a timeless eternal dimension, without beginning, and without a end, and therefore does not need a cause.

And you know all of this, how exactly? You're just pulling stuff out of your hat right now. It would be far more intellectually honest for you to say "Without evidence, I don't know for certain".

In fact I can trump that - The Invisible Pink Unicorn dwells in a truly timeless eternal dimension that makes God look finite by comparison, for she alone is truly without beginning, and truly without a end, and therefore does not need a cause. Yeah. Go me.