I was given this same message about Mom when I was 16. She would be healed "if I had enough faith." Fortunately, for those who told me this lie, when she died I was whisked off 1500 miles away.
You know what you get if you prepare for death, and find out God dies a miracle? Happy, happy happy with God for the longest time.
You know what you get if you prepare for life and death comes? Anger at God.
I am still very happy God gave you life. I wish you'd accept that as a miracle instead of an expectation of what God must do every time.
Here's a plan. If all it takes is faith, you have faith for Happy and Rod. And then, if you're right, you can gloat, and they can laugh. But if you're wrong, at least she doesn't have to get mad at God, instead of you.