(DeCandido's novelizations of Anderson's Films)
The priest lived in the United Kingdom when he was young and later moved to Raccoon City with his sister, whom he cared for and looked after and also worked with at the church. He would usually preach about the 6:13 commandments and would sometimes base his own "laws" on God's sayings.
When the t-virus escaped from the Hive and the population was turning into undead, Umbrella quarantined the city limits. Unable to leave town, the Priest hid in his church with his sister, believing that the rising of the dead was in some way a punishment on the people from God for not following the laws.
It wasn't long before the living were outnumbered by the zombies and they headed for the Raven's Gate Bridge; which was not far away from the church, to the evacuation point which was later closed off when an infected man reached the front gate. In a struggle with the infected, the Priest's sister was bitten. Knowing what his sister would become but loving her forever, he tied her to a chair in his study and held onto a copy of the bible for the rest of the time.
Shortly after, Mackenzie, a telemarketer, arrived with a .44 Smith & Wesson Model 629 revolver asking for shelter. At first, the Priest was angry at his trespassing and berated him for bringing a firearm into a holy place, but allowed him to stay if he didn't go into the back, covering up the fact that his infected sister was there. Angus then referred to the church as "his" hiding place.
After all exits out of the city were sealed, Peyton Wells, Jill Valentine, and Terri Morales entered the church to seek safety but Angus hesitated to let them stay. With his sister constantly trying to eat him, he began feeding the church's dead occupants to her in hope that it would control her. Right after her presence in the church was revealed to the other survivors, she broke out of her chair and bit him. Jill Valentine would then kill both of them with a 9mm Smith & Wesson 5946 handgun.