A man dropped his trousers in Exeter Cathedral, damaged an altar crucifix and then punched a 70-year-old woman in the face, a court has been told.
Nicholas Courtney, 34, admitted causing criminal damage when he appeared at Exeter Magistrates' Court.
Courtney, of Smythen Street, Exeter, also pleaded guilty to unlawful and malicious wounding.
He was remanded in custody to be sentenced on 20 March at Exeter Crown Court.
Prosecutor Karen Ball said Courtney went up to the high altar and climbed on top of it, sending candlesticks crashing to the ground and damaging a crucifix as he leapt down to the ground.
Outside the main entrance to the cathedral, Courtney punched a 70-year-old woman.
The force of the blow knocked her to the ground, breaking her wrist.
In a police interview Courtney said he felt "something bad was about to happen" and he "lost it".
Katherine Todd, defending, said: "He is absolutely horrified by what he has done.
She said her client was "extremely sorry" and would do anything he could to turn the clock back.