St. Hilary of Poitiers (c. 300 – c. 368) was Bishop of Poitiers and is a Doctor of the Church.
A pagan convert, he is perhaps best known for his stance against arianism (the doctrine that Jesus Christ is not divine but separate from God) for which he spent four years in exile. Because of his stance against arianism, he is sometimes referred to as the "Hammer of the Arians” and the “Athansius of the West.”
Upon his return, he continued to try to purge the West of arianism and wrote several renowned theological works, including De synodis and De trinitate, as well as hymns.
St. Hilary is the patron saint against snakes and snake bites, and of backward children. His attribute is a snake.
His feast day, which is also known as Hilarymas, is 13 January according to the General Roman Calendar (which includes the Roman Catholic calendar of saints). Earlier, this date was occupied by the Octave Day of the Epiphany, and his feast day was celebrated on 14 January instead. Octave Day, by the way, is the eighth day after a feast.
In England, “Hilary term” starts after Hilarymas in English courts and schools. The designation originated in the legal system, which divides the legal year into four terms: Hilary, Easter, Trinity and Michaelmas.
Who said saints aren’t still relevant today?
Note: St. Athanasius of Alexandria (c. 293 – 373) was also an opponent of arianism and argued against Arius at the First Council of Nicea (in present-day Turkey) in 325. The Council was convened by Roman Emperor Constantine I and aimed to reach consensus on Christian doctrine. The result of the council was the Nicene Creed.
Athanasius is a Doctor of the Church (Roman Catholic) as well as one of the four Great Doctors in the Eastern Orthodox Church. His feast days are 2 May (Roman Catholic) and 19 January (Orthodox).