Creationism

But do You think that the Creator created Big Bang which created the universe? I assume, that if You believe in Big Bang, You can no longer believe in it as God's way of creating our universe, because You can only narrow down to two possible scenarios of the creation: God created the Big Bang and therefore, created the means of developing the universe, not the universe, or He WAS the Big Bang which makes Him more of a Creator, and less of a God, because, well, You don't really picture God as biggest explosion in history of the known cosmos, do You?

well you can have opinions in any way when it comes to creation, the big bang is the scientific idea, and genesis stories are more divine ideas, but it depends how far you go with it, some could believe god made the big bang, some could argue, if there was nothing, how could the big bang have been made etc.
there really doesn't have to be a logical idea on it, seeing as it happened 13.75 billion years ago, long before life of any sort existed, science is all about learning new things, but something like that will never be known, it's all open to debate and new ideas, and this is true as there are over 4200 religions, so that is about 4200 ideas for how we have came to existence.

You don't really picture God as biggest explosion in history of the known cosmos, do You?

An old man with a long white beard floating around in the clouds seems more friendly than an explosion but it's not a better picture of God since trying to fit the infinite into a finite picture always falls short or leads to absurdities.

A Pantheist would say God is indeed The Big Bang and all that came from it. Here are some concepts of God you probably don't hear about every day. I'll give a link for each but there's vast information available with a quick google.

Pantheism - http://plato.stanford.edu/entries/pantheism/

Deism - http://www.deism.com/deism_defined.htm

Panentheism - http://plato.stanford.edu/entries/panentheism/

I sincerely apologize for what's to follow, but it really is a good question regarding pantheism:
'is God in everybody's asses then?' Ricky Gervais (obviously).

it is you, in you and around you. the name is just where your belief comes from, and not really important

The names are the contours of the reality. The name is important.