Archbishop of Dublin Diarmuid Martin has urged last-minute shoppers to "rediscover another sense of the word austerity" in the countdown to Christmas.
In a seasonal message, the senior Catholic cleric acknowledged how many families would be looking forward to celebrating on Friday after years of belt-tightening.
But he warned the nation not to forget the lessons of Christmases gone by.
Calling for a "feast of integrity", Dr Martin said: "Things are improving in Ireland and many of us can celebrate and enjoy ourselves.
"Purchasing power has grown from the days of harsh austerity. Disposable income has increased and we may be tempted to go back to celebrate once again as we did in better times.
"But can we say that things are improving if we lose the sense of simplicity which is the hallmark of every aspect of the Christmas story?"
His message comes as Retail Excellence Ireland (REI) has predicted the busiest Christmas in eight years.
REI spokeswoman Lynn Drumgoole said: "Christmas is falling at the end of the week ... and the extra day will bring in a significant amount."
Speaking to the Irish Independent, however, Dr Martin implored Irish people - "even those who do not believe in Jesus Christ" - not to get swept away by the commercial festive frenzy. "Ireland is doing better," he said, "but Ireland has its homeless and those who are hungry and those who are lonely and those who despair.
"Ireland has men and women on long waiting lists and on trolleys in our hospitals.
"Yes, we can and should celebrate. But we have to rediscover another sense of that word austerity: an austerity of simplicity and sobriety and integrity, an austerity which focuses on what is essential and shuns overindulgence and extravagance."
Keeping with tradition, the 70-year-old is set to celebrate the most important mass of the year at St Mary's Pro-Cathedral in Dublin on Friday. And his Christmas homily will be beamed live around the world via webcam.