The Advertising Standards Authority (ASA) encouraged firms to "carefully consider" the tone used and research whether their marketing material could be inappropriate.
In new guidance issued on Thursday, the ASA said: "Easter is a holiday that holds religious significance, particularly for those of the Christian faith.
"It is also a cultural point of reference that marketers may use to engage consumers.
"Given the sensitivities surrounding people's religious beliefs, marketers must take care not to cause serious or widespread offence when using religious references in their campaigns in or around Easter."
Premier previously reported on criticism against Cadbury after the chocolate retailer was accused of removing the word 'Easter' from posters promoting its annual egg hunt (pictured).
Firms can use religious language and imagery as long as it is not done in a "mocking or disrespectful" way, according to the ASA.
The body previously ruled a cartoon crucifixion shown alongside the text "nailed on bonus", "dearly departed JC" and "sacrilecious [sic] bonus" fooled foul of rules because it was "mocking particularly sacred imagery".
But it determined that an ad showing a graffiti painting of Jesus wearing a rabbit costume was acceptable because it was "intended to highlight the commercialisation of Easter..."
It added: "While humour can sometimes help to reduce the likelihood of causing serious or widespread offence, the line when it comes to religion can often be very thin.
"You should therefore tread carefully and bear in mind that just because something might be considered funny by some - it will nevertheless be problematic if it offends a particular group."
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