The Christian era began during the reign of the first emperor of Rome, Caesar Augustus. At that time the Roman empire tolerated within its borders scores—if not hundreds—of religions and cults.
On its eastern border there was Persia with its Zoroastrianism; far to the northwest was the Druidism of Celtic Britain. There were popular Greek mystery cults. There were diverse forms of nature worship with secret initiations and fertility rights. Some folks had a superstitious attachment to astrology and others worshipped various sun gods.
The Romans themselves admired the religion and culture of Greece. They adopted Greek gods and blended them into their own religions. The result was a mixture of ancestor worship, emperor worship, and sun worship—a religion that included not one god, but many.
The Jews, on the other hand, worshipped only one God. Though surrounded by the images of Greek and Roman deities, they served a God they couldn’t see. They had no icons or images to represent Him. They had no initiations or fertility rites.
Instead they had a day. A day that set them apart. A day without equal in any other religion. A 24-hour period devoted completely to their God. The Jews had the Sabbath.