This is how God wants us to believe in His word - knowledge that is unshakeable. Unlike Thomas, who had to see the holes in the hands of Jesus before he would believe in the risen Christ, we must believe by faith. We were not there at the time.
I believe in many things that I have never actually seen myself. I am sure that Niagra Falls is real, as well as Antarctica and Hawaii. I may not know what lies beyond the sky when I look up, but I believe God is real.
John 3:16 - For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.