I think even if I was religious I still wouldn't say that God created it all.

But since I'm not religious, I also still don't believe that God created it all.
Even though the Bible may say so. (but that, I think, is a total different subject/discussion).

Apart from that, I wouldn't really know what else could have made all this.

In school they have thought us 2 things:
* in "faith"-class: everything was made by God
* in history class: it all started with a big boom

I founded that rather confusing during my school days.
And I still find that confusing, also knowing that they still teach that in schools nowadays.
Because how can 1 or 2 teachers, give different explanations to the same class?

But that's just me ^_^