I came across this car commercial today that makes great use of optical illusions:
I think this connects with faith very well.
If you are viewing the world only from the intended perspective of a specific belief or line of thinking, everything will appear as it has been made to. This can apply to different belief systems, or even different ways to understand a particular system of belief.
This is why it is important to be open to looking in from different perspectives. Some things that you were certain were solid objects or ideas may actually fall flat when approached from a different angle.