You are not describing logic but perception which would be the effect of saying "you see 2 but really there are 3 fingers" which is actually where that whole gag "how many fingers am I holding up" comes from.

Generally because your brain's frontal and rear areas control emotion and vision.

If you have 2 of something and 2 of something else you have a total of 4 things no matter how you try to argue against it.

But here's a perplexing thought - if you could think but you could not feel, taste, smell, hear, or see...what would your existence be? What would you think about?

PS Your question "are faithful not asking for enough evidence" is wholly stupid for the same reasons that your argument that 2+2 could ever equal 5 is "stupid". That is not to say it's not a fair question or point but that you are trying to argue it is the case based upon the argument that our realities are not certain.

To which I reply to you - fly through the ceiling using only your mind and prove to me that reality is not certain by altering it.

PPS

To answer our other question faith is a good thing the same way that artistry or science or any practiced skill can be a good thing. It is an innate human talent that should be exercised for a reason we do not understand - but for no less a reason than why we practice art, which has a wholly non-useful purpose in life.