Saint Patrick was never about green beer and corned beef. One of the Christian movement's boldest heroes, Patrick was by his own account a slave who escaped his harsh Irish owner only to be sent back by divine vision to evangelize his former captors. And evangelize them he did, almost single-handedly winning the nation's loyalty to Jesus by persuading them that the God of the Christians was much kinder than the bloodthirsty spirits they worshiped -- kind enough to die for them, rather than insisting they die for him.
Patrick was no myth. Read his autobiogaphy, or "Confession," here, or listen to it here.