When Adam chose separation from God (spiritual death) his mind and body also began to die.   

I firmly believe that most of the diseases in mankind are a result of grossly immoral sex acts not only between humans but also with animals.   

Once these diseases entered into the human blood, it was passed from mother to child.   As each generation explored its own perversions, the number and severity of the diseases increased.   

In the past 2 centuries we have learned how to cure or ameliorate the symptoms of many of these diseases but in so doing we have become licentious, trusting that science can fix whatever we bring on to ourselves.   

2000 years ago God became flesh and dwelt among us and is known as Jesus.   Jesus paid the price for our rebellion and enabled us to be reconciled to Him (by faith).   

In that reconciliation He has provided for our healing and freedom.   But, the ball is in each of our courts as to whether we choose to believe His Word and His Love and His Grace.   

No, God is not teaching you something through sickness and disease.   His heart is to heal you, but more than your healing, He wants you.   And the only way you can offer yourself to Him is in faith.   

You cannot demand His gifts - that would make you god.