I think it's saddening really that they can't see past anything they can't measure or observe.

It's not that they don't have the imagination or foresight needed to contemplate these things. It's that they find the exercise to be futile. Sure, you can have a pseudo-philosophical discussion on the nature of existence, or where we all came from, but you'll never truly be considering everything there is to consider, or looking at the issue completely objectively.

It's all about faith, and being humble enough to say "I don't have all the answers, and I'm okay with that."

Humility is definitely an important quality, regardless of if you're religious or not. But it's not exclusive to people who have faith! Practicing science generally takes this one step further - after the admission that you don't have all the answers, you resolve to try and find the answers as honestly as you can.

Certainly. But there will always be something I can't understand. To me, that's God.

By this definition, plenty of scientists and rational thinkers believe in God. But this definition of God is disingenuous; it's not the "God" that first comes to mind when you're posed a question.