Who says sickness is to our benefit? There are Christians who think this, that we ought to be grateful for our afflictions and find in them lessons God is teaching us .
In the writings of the Rev JR Miller which overall I like, yet I do not agree with him that sicknesses are blessings.
My major argument is that Jesus Christ spent a huge amount of time healing every kind of sickness. He wanted us to have life abundantly. How can anyone who is in pain have that?
First of all I think making statements like "sickness is to our benefit", or "God doesn't want us sick, He will cure all the faithful", are not statements that can even be true in all cases. Like you can be blessed through tribulation, just like seeming blessings can turn into curses, like winning the lottery. So these kind of statements are a bit audacious and just simply cannot hold water.
I do want to share with you an example of God used the brokenness of my body to bless me. It's not exactly "sickness", but I believe it applies. I was born and blessed with a pretty darn good body, fully functional and very capable of holding up to anything I wanted to train it to do. Really all I'm trying to say is I was very blessed with a healthy and capable body, that for the first 33 years of my life never one time thanked God for. So at 31 years old on 10-25-11 I was leaving my job and I hopped on my motorcycle to go home and woke up 19 days later in the hospital. After it was said and done I lost all function of my right (and dominant) arm. Was by far the worst thing that ever happen to me, and happen when I thought I was a Christian as well. I had already responded to the alter call, went up front, repeated the prayer, and then went to be baptized for good measure. I was declared saved by all the church leaders I knew.
I say that because the next two years of my life were a downward spiral. I honestly wanted nothing but to die. I can't feel my right arm at all so /I even had an easy way to do it without pain. I'd rundown everything around me like my work can replace my, my wife can find someone else to love her, my dad will get over it, all the way down to my two sons. I knew that no one could replace me there, no one could love my sons like their father does, or would fight as hard for them as me. So I was stuck. That didn't stop the suicidal thought that plagued my thoughts all day everyday though. I couldn't help it, I could make myself be better either. For two years solid everyday at least once every 5 minute I thought about killing myself.
Then after two years of that I was home alone for the first time in a while, and one Sept.29th 2013 it all came to a head and I hit my knees. I knew that the doctors couldn't help me, science couldn't fix me, money could do nothing, and even what I thought of as God at that point couldn't help me. I was hopeless and broken and saw myself for exactly what I was, and hit my knees in surrender. At this point I wasn't seeking God, wasn't telling Jesus "I'm ready now", nothing like that, I thought I'd already done all that and it didn't help. No when I hit my knees a said "I can't do this anymore, I can't do this anymore, I can't do this anymore, world you win, I lose, and I quit!!!" That was it, picked myself up off the floor, dried myself off, and went to bed.
The next day I got up and went to work like always, and it wasn't until lunch that next day that it hit me like a ton of bricks, I haven't thought about killing myself today!!!!" At that moment I knew two things,#1 Whatever this was, it was God, and #2 Jesus was His Son. I was born again that day and now 10 years later He is still using me and I love it.
So see now I pray thank you to Him for this hardship, still the hardest thing I've had to go through so far in life, I THANK HIM for it in truth because this was what He used to draw me into Him. This "sickness" ended up the most amazing thing that's ever happen to me because it opened my eyes to truth and reconciled me to my Creator. Best thing ever. So this is an example of how a sickness can be a blessing and something I could be grateful for.