Yeah, no kidding, Monsieur.
Take a history of science/medicine course sometime and you'd learn on Day One of the course that in ancient cultures (eg Egyptian, Mesopotamian) there was no differentiation between theology and medicine: both roles were played by the same individual (typically a priest), since the two were deeply intertwined to be indistinguishable. Fact is, belief in Gods (Ra, Azuru Mazda, Jehovah, etc) once WAS the best-available science of the day!
Eventually though, Greek thinkers like Aristotle soon began to tease out medicine from theology, where eg Aristotle's heretical suggestion (circa 300BC) was that epilepsy wasn't caused by angry Gods, but by a organic process occurring in the brain.
However, unenlightened thinking still persisted in vast parts of the World, such that even in Jesus' day he travelled amongst largely-illiterate and uneducated people in Palestine who still believed illness resulted from sins, which was the basis for performing miracles of healing: Jesus claimed to be authorized by God to be able to forgive sins, so THAT was how he healed, resurrected the dead, etc. Even in 30CE, the priests in the rebuilt 2nd Temple in Jerusalem were STILL curing leprosy, which is why Jesus cured a leper, but told the person to go to the Temple and report to the priests and present the required offering, per the Law of Moses.