A TV advert for mince pies, which featured a nativity play with a graphic hospital-style birth scene, attracted the most complaints of any ad in 2004.
More than 800 people objected to the Mr Kipling advert
More than 800 people objected to the advert for Mr Kipling which Christians claimed mocked the birth of Jesus.
In all, adverts using religious imagery prompted the most objections, the Advertising Standards Authority said.
A poster echoing Leonardo da Vinci's The Last Supper for Channel 4 series Shameless led to 264 complaints.
Regulator Ofcom, which ruled on broadcast adverts until it handed over the task to the Advertising Standards Authority on 1 November last year, upheld the objection against the Mr Kipling advert.
It ruled that the advert breached their code, was offensive and the advert was subsequently taken off air.
But the ASA rejected the claims against the Channel 4 posters, saying they poked fun at the painting rather than religion.
The Shameless poster ridiculed art not religion, the ASA ruled
Another poster campaign prompted a number of complaints. This time it was advertising the morning-after pill with a slogan which posed the question: "Immaculate Contraception?".
A total of 182 complaints were made from people who again felt religion was being ridiculed.
The ASA ruled that the pun on the Roman Catholic belief of Immaculate Conception could cause widespread offence and upheld complaints against it.
In its annual report, published on Tuesday, the ASA said it had seen a record 1,835 non-broadcasting adverts dropped or changed after the watchdog's intervention.
These included an Armani Junior advert which the ASA ruled sexualised a child whose gender was ambiguous and a Ryanair promotion which promoted "Fawking Great Offers" close to Guy Fawkes Night, which the watchdog ruled the Ryanair advert was offensive.
The report also showed that between the time the ASA took over Ofcom's broadcast remit on 1 November and the end of 2004, 1,797 TV and radio advertising complaints were made.
One of the first TV adverts the ASA dealt with was Tango, which saw a young man rolling down a hill with some concrete pipes and crashing into a tree.
The family of a child who had died while playing with concrete pipes complained and the ASA ruled that it was likely to appeal to children and was consequently dangerous.
ASA chairman Lord Borrie QC said the broadening of the ASA's powers meant it was now easier for customers to complain.
People had a "one-stop shop" to go to which was accountable to the government, Ofcom, advertisers and consumers, he said.