As Father Robert Fayers delivered his sermon on the Apocalypse parishioners at St Michael's Church listened with due attention.
That was until - as warnings about the end of the world filled the Grade 1 listed building - a lead drain pipe smashed through the roof.
The almighty bang sent shudders through the congregation as roof panels tumbled off the church into the road amid heavy winds.
The piping left a gaping hole in the roof and Victoria Road in Brighton remains cordoned off.
Father Fayers said he had been discussing the end of the world at the service and had moved onto mass when there was a "great bang".
A panel had tumbled off the bell tower, dislodging the guttering and down pipe which crashed through the roof of the Lady Chapel, which includes some of the most important pre-raphaelite stained glass in the country.
Father Fayers said: "The theme for Advent Sunday was the last things, the Apocalypse and the end.
"With the whooshing of the wind around the church it sounded as if the world was about the end.
"I did assure the congregation that I hadn't arranged for the sound effects.
"The Lady Chapel has been described as a Fabergé Egg and we are very relieved there has not been significant damage."
Work on the roof should begin by the end of the week and is estimated to run into thousands of pounds.
Although the hole means that the ceilings has been left open to the elements, water has not seeped through to the chapel and important artifacts have been protected.
Father Fayers said despite the problems, mass is being held as normal in the run-up to Christmas.
The church, high up in the Montpelier and Clifton Hill area, is actually made of two places of worship, both built by renowned Victorian architects.
The first was designed by Bodley in the 1860s and now forms the south aisle of the church.
In 1893, work began on an extension by William Burges, which dwarfed the original structure and has became the main body of the church.
Writing for The Guardian, journalist John Keenan said: "The reason why a visit to the church is mandatory for any serious art lover lies at the other end of the aisle in the Lady Chapel.
"Below a marvellously detailed chancel roof are four magnificent stained-glass windows which, for me, are the most superlative examples of their type in the country. "
The high winds and pounding rain of Sunday caused damage across the county, tearing down up to 70 trees and flooding major thoroughfares.
Part of the roof at Worthing Station was blown off and firefighters had to use an air ladder to repair it.
The corrugated roof of a garage in River Road, Littlehampton, was also damaged and required attention from the fire brigade.
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