God-believers only: Why did God create a universe so big? (read this)?

I'm busy reading a fascinating e-book entitled "God as part of the Brain". It explains how the world started from Big-Bang to how we were formed through completely "natural" and "unsupernatural" phenomena within 20 or so pages (I'm still reading the 3rd chapter). The question is, if God's purpose of creation was to create humans on Earth, what's the point of billions of years of evolution and creation and a universe so vast when we are only on planet Earth which is barely a small dot in the whole cosmos. I'm Muslim, but these questions are haunting me. I don't believe in blind faith. There must be a logical explanation and please don't bombard me with "Only God knows" stuff, because I want to be convinced.