Question

what were the reasons of the setback of ancient Olympic ​

Answer 1

The ancient Olympics were as much a religious festival as an athletic event. The games were held in honor of the Greek god Zeus, and on the middle day of the games, 100 oxen would be sacrificed to him.

The ancient Olympics, held every four years, occurred during a religious festival honoring the Greek god Zeus. ... With the rise of Rome, the Olympics declined, and in 393 A.D. the Roman Emperor Theodosius I, a Christian, abolished the Games as part of his efforts to suppress paganism in the Roman Empire.