The biggest political event in Christian history is the conversion of Constantine, the first emperor  that not only expelled the Christians, but strongly supported the Church, turning it into a super-rich and powerful institution. The roots of empathy of Constantine to the new religion is unclear ….
In 312 AD, the battle with Maxentius (son of Maximian, whom Constantine killed or forced to commit suicide in May 311) in Moulvia bridge (now Ponte Molle) two kilometers outside Rome, saw the monogram ” CHR “with the inscription” In this you win “as Eusebius testifies, saying that the emperor told him himself .

Constantine did not speak Greek. The Latin expression is “in hoc signo vinces”. Eusebius delivers that Constantine saw the “XR” in the daylight, under the Sun, two weeks before the battle, while Laktanios saw the symbol in his sleep the night before. Eusebius did not mention anything about it in his church history, but in the biography he wrote about  Makarios Life of Constantine, who wrote twenty-five years after the victory of Constantine over Maxentius.
One of the biggest difficulties is that the decryption of monogram “HR” was not a widespread symbol and not found in any Christian symbolism till then. Contrary to what Pagans were making a “good” or beneficial “extract text, implying the word Christ. However the “XP” is the thirty-sixth and last letter of the Armenian alphabet … suggesting that Christ is the A to Z. This monogram appeared on imperial helmet in the spring of 315, three years after the vision. Personally I do not rule out the dual meaning or use for some time until it was won by Christian …. another interesting version,of  what Constantine saw in the sky was a very ominous conjunction between the planets Mars, Saturn, Jupiter and Venus,at  the constellations of Capricorn and Sagittarius. To avoid unpleasant feelings caused the army, turned the symbol into a positive force ….The subsequent victory of Constantine justify his conversion to the Christian God, who became his patron. Because he was illiterate and superstitious, after winning believed firmly that it was under the favor and protection of the Christian God.Ending with the vision seen by Constantine, we mention the view of Jones, who expresses the possibility this was a rare but scientifically validated form of the halo phenomenon.This is analogous to the rainbow, like that typical and transient.It is being created when sunlight is incident not raindrops, but ice crystals. Usually the form parhelion or light rings surrounding the sun but scientifically observed in some cases the formation of a light having the cross in the center of the Sun ….