From the year 235 through 284 AD the Roman Empire became so unstable, nearly collapsing. In Roman history this period is known as The Crisis of the Third Century. The empire suffered from invasions, civil wars, and economic problems. The crisis was triggered by the assassination of Emperor Severus (see Fifth Persecution) after which a power struggle ensued which lasted for about 50 years! This led to the empire disintegrating into three competing states, namely the Gallic Empire (consisting of Gaul, Britannia, and Hispania), the Palmyrene Empire (eastern Syria, Palestina, and Aegyptus), and the Roman Empire (Italy).
Aurelian was a mighty emperor who engaged in various wars which led to victory over the Gallic and Palmyrene empires. Aurelian was eager to subdue all the territories and thereby restore order and the glory of the Roman Empire. This he accomplished and thus ended the Third Century Crisis, earning himself the title “Restorer of the world”.
“One faith, One Empire”
It is interesting to note that Aurelian wasn’t just interested in political unity; he desired to establish one religion wherein all the people, despite having their own gods, were supposed to worship the Sun god as the main deity of the Roman Empire.
25th December – Birth of the Sun God
A new temple, built in 274 AD, was dedicated to the Sun god on 25th December. Aurelian’s doctrine was “One faith, One Empire”. However, this doctrine only came to be fully enforced during the reign of Constantine the Great when Rome embraced Christianity. As stated in Britannica Encyclopaedia, Aurelian “sought to subordinate the divergent religions of the empire to the cult of the Unconquered Sun (Sol Invictus) and so create the kind of religious unity that came only later with Constantine.”
During Aurelian’s reign persecutions of Christians took place. John Foxe notes that Felix, bishop of Rome, was the first to be killed in 274 AD. There was also another believer called Agapetus, who after selling his estate gave the money to the poor. He was arrested, tortured, and beheaded.
Following the death of King Shapur of the Sassanid Empire Aurelian wanted to seize the opportunity to attack the empire. It was during his advances towards Persia that he got murdered by his own people.
After Aurelian’s death his successors ruled for short periods before being killed. Tacitus had succeeded Aurelian but died of a fever. The new ruler, Florianus, only ruled for three months before being killed by his own soldiers. Then came Probus who was also killed by his disgruntled soldiers. The new ruler, Carus, was killed by a lightening! During the reign of these short-lived emperors Christians enjoyed some peace. However, what would be the worst persecutions were just about to start during the reign of the next emperor, Diocletian.
Maximian decimates 6,666 Christian Soldiers
When Diocletian became emperor, he appointed Maximian as ruler over the western empire. This evil Maximian had ordered his soldiers to march over to Gaul to quell a rebellion. He ordered them to offer a pagan sacrifice and to swear that they would participate in the killing of Christians in Gaul. The soldiers could neither make the sacrifice nor take the oath. Maximian became angry at this and ordered for every tenth soldier to be slain with the sword. He hoped for the remaining soldiers to feel afraid at the killings but it was not so. The remaining soldiers could not offer the sacrifice or take the oath. A second decimation was ordered, then the third, until all six thousand, six hundred and sixty-six soldiers all got killed!
Various other persecutions occurred against Christians, but all these cannot be compared to those which occured under Diocletian.
 This date is believed, by some Christian writers, to have been later adopted for Christmas celebrations. This was after Pagan Rome converted to Christianity during the reign of Constantine the Great. Like Britannica Encyclopaedia notes:
December 25 was first identified as the date of Jesus’ birth by Sextus Julius Africanus in 221 and later became the universally accepted date. One widespread explanation of the origin of this date is that December 25 was the Christianizing of the dies solis invicti nati (“day of the birth of the unconquered sun”), a popular holiday in the Roman Empire that celebrated the winter solstice as a symbol of the resurgence of the sun, the casting away of winter and the heralding of the rebirth of spring and summer. Indeed, after December 25 had become widely accepted as the date of Jesus’ birth, Christian writers frequently made the connection between the rebirth of the sun and the birth of the Son.
While it may be difficult to comprehend how the early church, which was so “intent on distinguishing itself categorically from pagan beliefs and practices”, could so easily Christianize a pagan idea, it is important to be aware that there are many other unscriptural teachings which crept into the church unawares.