Who Is Sol Invictus?
Thegod of the Unconquered Sun, Sol Invictus,was the official sun god of the laterEmpire of Rome.The Emperor Aurelian reintroduced the sun god and cult in 274 AD. TheEmperor Constantine,also known as Constantine the Great,madethe practice ofChristianity legalin Rome, but continued to have his coins inscribed with the words, “Sol Invicto Comiti”, which meansCommitted to the Invincible Sun.
The birthday of the unconquered sun was celebrated at the Roman festival of Dies Natalis Solis Invicti onDecember 25,and it is often theorized thatConstantine had a hand in selecting this day as the celebration date of the birth of Christ as well.
Constantine the Great
“The struggle for deathlessness must be free”, are the words of the Emperor Constantine, who legalized Christianity in ancient Rome. As the story is told, he was preparing for a great battle with Maxentius to gain control of the western portion of the empire, and considering what power to rely on for protection. He could look to the many deities or a single god almighty as presented by Christianity. As he decided to take the Christian route, he claimed to see a radiant cross above the sun that was scripted with the words “In hoc signo vinces”, which means “by this sign conquer”. This was painted on the shields of his army prior to entering the battle. Constantine’s forces prevailed. Maxentius and his army retreated to a bridge across the Tiber River, and Maxentius drowned.
Seemingly, Constantine associated his victory with the power of the sun, and viewed Sol Invictus as very similar to the Christian god. Hisadoption of Christianity in the Roman Empire was more likely a matter of political strategy than religious conviction.
https://mythology.net/roman/roman-gods/sol-invictus/