I KNOW BECAUSE I SEE
The fingerprints of God are everywhere in nature! Faith - at least in part - is the spiritual seeing or perceiving of the fingerprints on the things he has made. We see the order, the beauty, the greatness, the complexity of what he has made - and these are the evidence that God made the world as he said!
But we have to be looking to see it. I have friends whose house is full of hidden 3-D image posters. At one level are one thing, but at another level, quite another. At first glance, all you see is the surface presentation. But let your eyes focus through the page and , you may see something else not only appearing, but actually standing up off the page.
Some can stare and stare, and only see the surface. Others see almost immediately the head of Abraham Lincoln or a lamb. If someone says, "How do you know the lamb is there?" you reply, "Because I see it!" Your seeing is your proof, your evidence. Someone else may not be able to see it, but it won’t change your mind!
So some people look at the universe God created and only see color and chaos and the surface. Others have a deeper view and suddenly God’s fingerprints come into focus. And no one can talk you out of it.
So when the author of Hebrews says in 11:3 that we understand by faith that God created the world, it is not that faith is just a response of the soul - it is also a perceiving or understanding act. Understand means "to perceive with reflective intelligence."
Faith is a spiritual act that uses all the intelligence God has given a person; an intelligence that reflects, and sees the fingerprints of God and acknowledges his hand at work. It doesn’t mean you believe them into being - that would be wishful thinking, positive thinking, which is not authentic faith. Real faith is based on real Truth. It looks deeply at the world God has made - looks through it, so to speak, and by the grace of God it sees the glory of God standing forth off the creation like a 3-D image.