Peter Clifton is one of three siblings born to a family of medical traditions. From a young age, Peter loved church and faith and as he grew up, decided to give his life to Catholicism. This caused great strain between him and his father, who would not forgive him for his decision of priesthood instead of becoming a doctor.
He became a Father of the church and was placed at St. Augustine's Catholic Church in New York City under Father Malory. He and Father Malory bonded quickly, becoming great friends as well as Malory filling the role of father figure for Peter.
One night, a naked woman found her way to the church and he and Father Malory allowed her to stay at the church with them. Peter would soon learn that she was a fallen angel named Avengelyne and they soon formed a great bond. Peter was then kidnapped by the demon H'Lana to get to Avengelyne. He was rescued and later returned the favor by saving Avengelyne from the evil demon by beheading her.
Learning the truth of Alexander Belisle (actually the demon lord B'Liale), Peter suggested an ancient exorcism ritual he had heard of long ago. Using Avengelyne's blood as a replacement for Christ's blood (they were both the children of God), they were able to cast B'liale from Earth and stop his plans of world domination.
When St. Augustine's was burned to the ground by demons, Father Malory started his own church called the New Church of the People. Remaining Catholic, Peter got a position at St. Patrick's Cathedral.
At some point, he became the head of the New Church of the People.