In the Gospel of Matthew the Man of Galilee makes an extraordinary claim:
Then Jesus came to them and said, “All authority in heaven and on earth has been given to me."
However, risen Lord Jesus having all authority in heaven and on earth has not wiped out human diseases nor has He prevented illness among other living organisms. The dictionaries of various types of illnesses are thick and detailed concerning all parts of the human body and mind. Hospitals, big or small, are built everywhere human live and medical research and profession flourish.
"The deadliest disease in humans is ischemic heart disease (blood flow obstruction), followed by cerebrovascular disease and lower respiratory infections respectively" (WHO 2012). Fearsome pandemics have wiped out large human populations in the past and threaten to do so in the future, as well.
In fact, Lord Jesus - almighty Christos Pantocrator - did not promise in the final words of the Gospel of Matthew to wipe out human diseases. His focus in those words was on something else altogether.
Divine will and illness
In our judgment omnipotent God could have created a bit more perfect world without diseases. His work looks deficient as so many details can go wrong from birth to childhood, adult life and old age causing suffering, pain and often early death.
Again, as in the case of wars, the easy solution is to deny God and all wondering of His plans and good will towards humanity so praised by the angels in first Christmas in the shepherds field. For if God is capable of creating a human that does not become sick under any conditions why did He not do so? The responsibility of the faults in the system lies ultimately on the Maker.
In same breath we could then ask why diseases, why suffering, why death? Why God did not create immortal humans? Why we all have to die?
Holy Scriptures are not Utopian nor do they describe human world in sugary words and beautiful but untruthful words. The life of the Chosen People is filled with suffering and the Torah contains so many references to sickness and how the community must deal with specific cases such as leprosy. Job is hit by all kinds of diseases to test his love of God and sacrifices of thanks are offered in the Temple after recovery from illness.
Human diseases are integral part of Scriptures and the role of Jesus of Nazareth as a healer among the people of Galilee, Judea and Samaria is pronounced in the Gospels. His disciples continue the healing service in specific cases. The resurrection and the authority given to Jesus did not bring a fundamental change in this world.
The focus of Jesus' words at the end of the Gospel of Matthew is in something else altogether.