You cannot believe anything without assuming that what you see is real atall to begin with. So everything is an assumption if you are as picky as you folk seem to be.
You even assume that what you see will always be the same, why? Why does your knowledge work so well in this apparantly non-knowledgeable universe?
Going to put it down to nothing? Well nothing is evidently capable of bringing about intelligence too then 😉.
I stand by what I said, if what I believed was worse than what you did, I wouldn't believe what I do.