It was Constantine.

Have you have ever wondered how Sunday became the most “important” day of the week? Well, here this is how it happened. It was Constantine the Great who set the seal on the seven day week. Without his conversion to Christianity, we might not have our current form of the week.

Constantine ruled as a Roman Emperor from  306 to 337 AD. He was responsible for enacting many administrative, social and military reforms. One of his most important moves was the introduction of the solidus, a pure gold coin that became the standard of “international” currency for more than seven centuries. Look closely, Constantine’s face was depicted with Sol Invictus the official Sun god of the Romans, with whom he identified strongly.

The Roman Empire, up to this point in time, was known for the great number of religions that were practiced within its influence.  Early on the Greek gods had been adopted and given Roman names. These personifications of the five planets, the sun and the moon, were largely conducted at certain hours at household shrines. Secretly soldiers and administrators attended to Mithras, an ancient Persian deity. There were private gatherings for women to pay respect the Vestals. The Jews, once a conquered people, had been given the rights of citizenship including the freedom of worship. Only the Christians suffered bitter attacks due to the fact that they repudiated all other gods.

Even with all this diversity the Roman rulers felt religious tolerance to be a stabilizing force and responsible for their greatness. Still they promoted their religion over all the others. The Catholic Encyclopedia states that Constantine was the last of the emperors who tried to merge the beliefs of the empire. “…many of the emperors yielded to the delusion that they could unite all their subjects in the adoration of the one sun-god who combined in himself the Father-God of the Christians and the much worshipped Mithras; thus the empire could be founded anew on unity of religion. Even Constantine, …  for a time cherished this mistaken belief.

In 313 AD Constantine and his co-ruler Licinius issued an edict stating that Christians were to be allowed to follow their faith without oppression. It is not that clear how Constantine became personally acquainted with Christianity but it is thought that his mother, Helena, may have been Christian convert.  We know that Constantine declared himself a Christian around the age of forty which came about due to a religious vision on the battlefield.

Constantine decreed Dies Solis, the day of the sun, as the Roman day of rest in 321 AD. “On the venerable day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed. In the country however persons engaged in agriculture may freely and lawfully continue their pursuits because it often happens that another day is not suitable for grain-sowing or vine planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost.

Constantine apparently realized that Sundays were already being used to worship Sol, Christ and Mithras by their respective adherents. He seemed to have sensed the association between these three religious figures and the triumphant Sun Archetype, that we “officially” celebrate every week on Sunday.