A close relative of mine is dying of cancer: sent home from the hospital on hospice. I was talking with him the other day and he tells me he thinks God is healing him. "I've felt better the past few days," he says. "And, I've cut out tortilla chips and some other bad things from my diet." God and diet are doing the trick.
A couple of years ago, a good friend of mine died of Lou Gehrig's disease. Same thing, "I think I'm going pull through this," he told me. His twin brother had died of the same condition a year previously. He died a few months later. He was a great guy. Great guy.
I believe God heals people. I hope God heals people. I know doctors and drugs heal people. I use "believe," "hope," and "know" purposefully.
One time, I'd been hiking all day with a group of about 10 other people. Around dinner time, we said a prayer and asked for strength. While the prayer was happening, I felt something in my legs. I kept going for another 5 hours and had energy that really surprised me. I've hiked a lot. I know what it feels like to be tired. I know I had energy on a level different from other hikes. I believe God had something to do with that. I share this story because I have personal experience leading me to believe God can make adjustments to my body. I assume he can to other people as well. : )
Anyway, my relative is going to die, of this cancer, in the next few months. He's not going to be healed. I believe God could, if He wanted, heal him. He's not going to. Maybe it's comforting for my relative to believe this. OK. I guess he's allowed it. And, if it helps; who hasn't found comfort in a bit of irrationality at one point or another.
I don't think it's faith though. I think maybe it's hope. Faith, as I define it, has some condition of being in alignment with God's will. If God's will isn't there, it might fall under an expansive definition of "hope." You can hope for things that aren't true. I wonder if Christians sometimes do their faith a disservice by conflating this "hope" with "faith." Non-Christians might think "faith" is silly because it's so often in things that aren't true. If you, instead say, "I have hope God will heal me," maybe that's more accurate.