At this time of the year, donations soar, the papers are full of appeals, and everyone suddenly rediscovers generosity.
This 'big give' clearly relies on 2,000 years of belief, sentimentality and guilt rather than the persuasive efforts of good deeds, remembered once a year by the sozzled turning up to midnight mass.
The challenge for charity isn't to raise money when many more give, or give more. Instead, it is to secure funds year-round, convert occasional givers to regulars, tap new generations to be generous, attract a rising proportion of GDP, and seize the opportunities of new ideas, media and technologies.
Yet less of our GDP goes to charity today than it did a decade ago, only 30 per cent of giving comes with Gift Aid, just 13 per cent of legacies include donations, payroll giving's growth is slowing, online giving is often treated as an afterthought, chuggers rule, and the margin on charity Christmas cards can be pathetic.
At a time when the wealth gap is widening and surveys suggest taxpayers - led by the young - are becoming meaner about welfare payments, perhaps charities should recall why they need their own funds.
Surely it's because in helping others, charities are also about causes, change and the freedom to do what is right, and not just treating the symptoms of others' failure by taking on service contracts and keeping their mouths shut. Christ didn't get nailed to a cross so that low-paid charity staff could become skivvies for a government papering over cracks in the welfare state, spending more on arms than aid, and leaving asylum seekers to starve on the streets while their children are cast into care.
As Lennon said: "So this is Christmas, for weak and for strong. For rich and the poor ones, the world is so wrong."
Nick Cater is a journalist and media consultant. He can be contacted at firstname.lastname@example.org.