St. Patrick's Day was known throughout the Roman empire as the day of apotheosis of the god slain during the Ides of March: Liber Pater or Mars Pater, who would have been known as Patricius or Patrick in Britain. At his Roman festival on March 17, a gigantic phallus was paraded through the streets, and solemnly crowned with a garland representing the divine yoni. The phallus of Liber Pater was also known as the Palladium, planted in the womb-temple of Vesta.
An old chronicle mentioned a Roman-Irish martyr called Bishop Palladius, "the first bishop to the Irish who believe in Christ," sacrificed to the Irish Moon-goddess before Patrick appeared. Evidently both Palladius and Patrick were the same pagan god, adopted into canon after his old shrines were taken over by Christians.
The patron saint of Ireland was probably a fictitious figure created from Roman pater or patricius, a priest. The "proof" that he existed was from his own autobiography which was supposedly written in the 5th century but not discovered until 400 years later according to the Encyclopedia Britannica. His writings were probably forgeries by monks who wanted to pretend that Ireland was Christianized earlier than it actually was. In the 12th century St. Bernard complained that the Irish were still given over to "barbarous rites," because Christianity had failed to take root (De Paor, M. De Paor, L. Early Christian Ireland 1958 [London]).
Like many other saints who evolved from pagan roots, St. Patrick had pagan precedents. One was the Irish God of the shamrock, Trefuilngid Tre-eochair, "Triple Bearer of the Triple Key". He was a son and consort of the Triple Goddess whose triple yoni was represented by shamrock designs from the earliest civilizations of the Indus valley. The Irish worshipped the shamrock as a sign of their triple pagan deities. The book of Leinster said that Patrick's mother was the Goddess Macha, one of the trinity who gave birth to the shamrock-god.
Lewis Spence in the History and Origins of Druidism says that Patrick was educated by a Druid.
