The emperor before him was Gordian III who began to rule in 238 at the age of 13. Gordion had appointed Philippus to be his praetorian prefect in 243 after the previous praetorian prefect, Timistheus, had died in battle. Seeing an offer of the kingdoms of the world and the glory thereof, Philippus gladly gave his soul for it. Using a shortage of food as a pretext, Phillipus told his men that it was better to be ruled by a man than by a boy. And so, in 244, Philippus had Gordion assassinated in Zaitha and himself proclaimed emperor. For six years he ruled the "civilized" world, until his own soldiers killed him in a battle in Verona.
Later tradition honoured Philip as the first Christian Emperor, but this was certainly false. (OCD, 816).After all, what in the conduct of Philippus would lead one to the conclusion that he was Christian?