St. Hilary was a bishop and a doctor. Hilary was born to pagan parents in Poitiers, France. He was later exiled for defending Christian beliefs. Hilary married and had one daughter, Afra. All who knew Hilary said he was a friendly, charitable, and gentle man.

Hilary had a thorough education; his studies led him to read scripture. He became convinced that there was only one God whose son became man and then died and rose from the dead to save all people. This belief led him and his wife to become Christians. The people of Poitiers were impressed with Hilary and chose him to become their bishop.

Hilary spoke out against Arianism. He warned people of this heresy that denied that Christ was God. When the Emperor Constantius II wanted Hilary to sign a paper condemning Saint Athanasius, the great defender of the faith, Hilary refused. The Emperor was furious and exiled Hilary to Phrygia. While in exile for three years, Hilary did even greater good through his preaching, writing, and suffering.

Hilary's writing shows that he could be fierce in defending the faith, but in dealing with the bishops who had given the Arian heresy, he was very charitable. He showed them their errors and helped them to regain and defend their faith. Although the Emperor called Hilary, "disturber of the peace"; Sts. Jerome and Augustine praised him as the "teacher of the churches".