If one believes in it, faith is a function of grace. Some people, who don't want faith, have it and some people, who want to believe, don't. Obviously, questioning and doubt about faith come into the picture and does "reality". If one has faith that the bus isn't going to knock one down and it does, then one has to revisit one's faith.
But a couple of observations. As an earlier poster said, faith doesn't need to convince other people. Don't like it, don't keep involving oneself in it. It's a metaphysical construct that, if it works, works for each individual or group of individuals who have it.
Secondly, it's a subjective attribute that may, or may not, reflect an objective reality. God, or whatever notion one wants to use, either exists objectively or doesn't. Whether he exists or not is not dependent on one's belief or lack of belief. So sure there is an element of delusion or illusion about faith. If one wanted to organize one life around one's faith in Greek Gods and that worked for one on some level or another, the objective fallacy of what one believes in isn't really relevant to the quality of one's faith.
Leaving aside the poetic or metaphorical aspects of that kind of faith, I happen to think that faith in the scientific method is more reliable, a step up from older ideas of reality. But, even then, on the edges of science there are vast unknown areas, where one simply doesn't know if the same rules apply. I'm not positing an equivalency between religious faith and scientific faith, as the latter can be verified in ways the former can't, but I don't think that one need presume that science as we know it is the end of the story.
As for why folk can't talk about these subjects without losing their cool, one only has to look at the nature of the posts to see that its people attacking their fears and self-doubts about their own beliefs. If one's lucky, they may have read the post they're replying to, but, as often as not, it's clear that they've made no effect to understand or empathize with any argument that contradicts their own preconceptions or faith.