Parents of youngsters celebrating their First Holy Communion spend almost 1,000 euro on the day, making the religious industry worth 57 million euro, according to a survey.
Nine and 10-year-olds who received the sacrament were earning on average 468 euro in cash gifts on the day and later spending half of it.
John Monaghan, national vice-president of the Society of St Vincent de Paul (SvP), said parents will spend because they do not want their child to stand out from others.
"Our recommendation is to put a little sanity back into it, we need some sense," he said.
"It was never right. It was never justified. It is taking away from the sacrament and focusing on the showbusiness. There are a lot of families who cannot afford to do this."
A survey of First Communion habits found spending on the day down 17%, from 1,165 euro to 967 euro over the past two years, while the amount of cash youngsters collected was down 18%, from 574 euro over the same period.
In the years before the recession it was not unusual for parents to hire limousines and bouncy castles, and shell out on expensive dresses, suits, make-up and spray tans.
The study of 1,000 people at the end of May and start of June by Millward Brown Lansdowne for Ulster Bank found children in Dublin earned most, 533 euro, while First Communicants in Munster got 519 euro. Those in Ulster and Connacht were least well-off, getting 369 euro.
A spokesman for the Catholic Church in Ireland said focusing on money and gifts rather than the spiritual side of a sacrament is not good preparation.
"The First Holy Communion and Confirmation ceremonies are important days - landmark days - and should be memorable, proud and happy occasions," he said.