A man climbed on top of a cathedral altar after pulling down his trousers, broke a crucifix and punched a 70-year-old woman in the face, a court has heard.
Nicholas Courtney, 34, claims he walked into Exeter Cathedral to pray before being overcome by the urge to "give everything to God".
He placed £20 in a donation box by the high altar, before stripping off his trousers - exposing his buttocks to horrified worshippers and visitors.
Courtney then ran to the cathedral's high altar and jumped on top of it, causing a cloth covering it and two candle sticks to come crashing to the ground. Exeter Crown Court heard Courtney leapt off the altar and broke a crucifix, before fleeing by the cathedral's west exit.
He first smacked an outraged onlooker after she began reprimanding him but became angry when she hit him back. Courtney next targeted a frail 70-year-old woman, who was posing for a picture with her young grandchildren outside the cathedral ahead of her fourth course of chemotherapy.
He punched her in her right eye, causing the grandmother to fall to the ground and break her wrist. Stunned members of the public outside the cathedral were able to pin Courtney down and restrain him until police arrived.
Tattooed Courtney later pleaded guilty to charges of criminal damage and inflicting grievous bodily harm.
He will be sentenced at a later date. Judge Jeremy Griggs warned the offences were so serious they required a "substantial custodial sentence".
Prosecuting, Nigel Wraith said Courtney, of Exeter: "He removed his trousers, he exposed his buttocks."
He described how a 70-year-old woman had been posing for pictures with her grandchildren, aged three and five, on the cathedral steps.
Mr Wraith said: "Her husband was taking a picture of her and her grandchildren when she suddenly felt a punch.
"A fist hit her hard in her right eye and it was forceful enough to strike her off her feet." The woman, who was terminally ill with cancer from a tumour in her back, put her left arm out to break her fall, causing her wrist to fracture.
Police rushed to the scene and arrested Courtney who said: "Oh God, what have I done? "I can't come back here, I will get a kicking. "This is God's waiting room, isn't it?"
In interview, Courtney told officers he went to the cathedral to pray but "lost it" when he arrived, for some unknown reason. He claimed he climbed on to the altar to be "closer to God", Mr Wraith said.
Courtney will be sentenced at Exeter Crown Court on June 6.