Paul’s thorn in the flesh was not sickness. The thorn was “the messenger of satan sent to buffet him”. He also said the thorn was sent because of the “abundance of revelation” given the Apostle.
A careful study of Scripture teaches clearly that the work of Christ on Calvary was complete indeed; and that He bore not only our sins, but our sickness also in His Body. All who sought healing from Jesus received. He never told anyone it was not His will. Never.
The nature of Paul’s thorn is inconclusive among Biblical scholars...some believe it wsa a physical ailment, others do not. A messenger of Satan could have brought an illness to bear.
The New Testament is full of Scriptures which describe Jesus taking on our sins. Yes, those who asked Jesus for healing during His earthly ministry were healed. But how does that translate into the notion that Christians are never supposed to be sick? If that’s true, why do believers die?
Sorry, I’m not into trying to control God. He can and does heal people, but it is entirely His will to do so, or not. He is not bound to do it.