I have never heard a child who believed in God deny their faith because of disappointment, war, genocide, etc., or terrible illness, even their own. Even terribly abused children will cling desperately to the hope that their parents love them. In a similar vein, from my own personal childhood, I cannot recall ever getting anything from Santa Claus that I asked him for at the store. Not one single Christmas. And yet, I was never disappointed, never pitched a fit, none of my friends or siblings ever encouraged me to “curse Santa and die”! It wasn’t disappointment with him that caused my lack of belief, it was being told by other kids.
I think this is the “child-like faith” that Jesus talks about. If even imperfect parents can love their children, and those children love in return, how much more should we love a perfect Father?