Arianism, proposed by Arius in the Third Century CE, proposed that Jesus Christ could not be God because God himself is unique and immutable. This would mean that Jesus Christ was created by God and therefore lesser. This was considered heretical and banned from Orthodoxy, but caught on in Germanic cultures. 

Developed approximately around 500 BCE by Gautama Buddha in Northeastern India, Buddhism first spread to Central Asia and Southeast Asia after a few centuries.  Shortly thereafter it spread into China, Korea, and Japan.

Zoroastrianism was the official religion of both the Achaemenid and Sassanid Persian empires.  It is still practiced today, though the number of followers that adhere to Zoroastrianism is low in comparison to religions such as Christianity  or Islam.

Although initially Rome's government persecuted early Christian communities, the Roman emperor Constantine tolerated Christians and even converted to Christianity himself; Christianity became the official state religion. The Athenian Empire and the Nabataeans existed before Christianity. The Hunnic Empire, a great enemy to Rome, was never Christian. The Mongol Empire had a Christian population that was tolerated but was never officially Christian.

Augury had been the preferred method of divination within the Roman Empire until the popularization of Christianity in the Fourth Century. Things even as important as matters of state would be solved with a visit to the augur. Ephor were ancient Spartan leaders. Pontefix Maximus were high priests, but they were not necessarily concerned with augury. Princeps was a term for the Roman Emperor.

The path of Buddhist philosophy is to attempt to reach Nirvana, this is done through meditation and the philosophy of the eight-fold path. Nirvana is the state reached were the practitioner abolishes ignorance and worldly cravings, and is therefore released from suffering.

Siddhartha Gautama, also known as the Buddha, was born into a wealthy and powerful noble family.

His family was neither poor, nor carpenters, nor merchants but rather warriors and landowners.

Moses, and the more secular historical figure Sargon, were both leaders who were recorded as being placed in baskets and sent down rivers as infants (for Moses this was the Nile, for Sargon the Euphrates). The Buddha, on the other hand, was raised in a pleasure palace with his family.

Known as the Hijrah, Mohammed fled the city of Mecca with his followers; this event marks the beginning of the Muslim calendar.

The death of Ali, Mohammed's grandson, is important to understanding the difference between Sunnis and Shias, but it is not the beginning of the Muslim calendar.

Mohammed's birth date is celebrated in some Muslim communities as the holiday Mawlid, but it is not the beginning of the Muslim calendar.

Mohammed's death is an important event in Muslim history but not the beginning of the Muslim calendar.

Mohammed's return to Mecca is a triumphant event in the history of Islam and the Middle East, but it is not the beginning of the Muslim calendar.

In the early 300s, Byzantine authorities adopted Christianity as the empire's religion. Archaeological finds from that era document this increasing Christianization, especially visual motifs such as crosses.

Although there may have been a vibrant counter-culture celebrating paganism, Byzantium did not suffer from widespread civil wars between pagans and Christians.

Mohammed lived in the 7th century, centuries after Byzantine authorities adopted Christianity.

Byzantine authorities never forced suspected to pagans to march over stone portraits of pagan deities, although this was actually a Japanese practice in the 17th through 19th centuries against suspected Christian communities.

Some Byzantine emperors were more religious than others, but they tended to rule with absolute power; as a general rule they were not hermitic and did not delegate political power to generals in the army due to religious beliefs.

People in the ancient world largely felt as secular as many people today, at least when it came to the circles of educated advisers and bodyguards surrounding the emperor; declarations of divinity were always troubling to some.

Caesar was Julius Caesar's name but became a title over time; he was considered a person whose actions were exemplified and to be followed by capable and militaristic men.

For many centuries Japanese emperors were forced to live near poverty, even having their household staff sell their signature in the streets of major cities to raise funds, because they were considered spiritual beings; Rome's imperial behavior never politically demeaned the emperor as a matter of ideological purity. 

Universities are institutions of education with legally binding academic freedom that stem from the Middle Ages in which groups of young scholars and a single teacher, often an older monk, would meet in a predetermined location and discuss matters of nature and philosophy; Rome had no such institutions.

No Praetorian in history ever declared himself emperor.