I replied, "Happy Christmas", or words to that effect and kept going.
If this had happened in Belfast, I suppose it would be regarded as a 'sectarian incident'. How should we regard such a thing in Dublin?
I haven't a clue whether this man is in any way religious or not. I'm guessing he isn't. Is it possible for someone who isn't religious to be 'sectarian', or else its moral equivalent? Of course it is.
In a similar vein, a few months ago I received a phone call from someone who attacked my "f**king Catholic religion" and said I should be "castrated and hung up on O'Connell Street".
Emails attacking my religious beliefs arrive in my mailbox from time to time, especially when a story is in the news that has people angry at the church again, and therefore angry at anyone who is a publicly known Catholic.
And, needless to say, there is a huge amount of this sort of stuff on the likes of Twitter and the various politics websites.
A freelance producer and presenter called me a "poisonous c**t" for saying Labour is pro-abortion.
Someone else described me as a "nasty woman-hating scumbag". I have also been described as a "snivelling s**t", "one weird freak", and "the most mendacious and unpleasant commentator out there".
Social media is bad at the best of times, but it was much worse than usual after the Savita Halappanavar story broke.
Even though we don't yet know exactly why she died, it didn't stop everyone rushing to judgment, and anyone who suggested that maybe our law on abortion had nothing to do with her death was regarded as fair game.
Senator Ronan Mullen, who is also against abortion, got it even hotter and heavier than I did. Several clowns joked on Twitter that they'd like to crucify him. One person said he'd bring along some rusty nails and they'd throw a party.
I've never made much of an issue of this kind of thing before, simply because I think that when you're in the public eye you have to expect your share of cranks.
But a number of things made me decide to write about it today.
One is the fact that pro-choice commentators and politicians have been trying to make political capital out of the abuse they've received from abortion opponents.
Some of this abuse does need to be exposed, even allowing for the fact that politicians and commentators have to accept a certain amount of abuse as part and parcel of being in the public eye.
However, let's not pretend that the abuse is all coming from one direction. In fact, on social media, the abuse comes predominantly from the Left because when it comes to politics, social media is dominated by the Left. Go on the likes of Twitter and thejournal.ie and see for yourself.
Once you oppose the Left on anything you can expect to be denounced as a "woman-hater", a "homophobe", a "'fundamentalist" or a "racist" because many on the Left believe all opposition to their agenda is motivated by bigotry, pure and simple.
This is an appallingly reductionist view of politics and is the exact equivalent of religious people believing that anyone opposed to them is opposed to the will of God.
The second thing that has made me write about the abuse directed at people on social media and elsewhere is what happened to Shane McEntee.
We've been so busy thinking abortion is the most divisive issue in Irish politics that we forgot it is the state of the economy that really makes people angry.
With the media looking out for examples of abuse directed at pro-choice public figures and commentators, we forgot all about the vitriol being directed at government politicians forced to defend another unavoidably tough budget.
Politicians have always been subjected to a certain amount of anger but in the past, once they closed their front door, they were able to get away from it.
However, social media has changed that because the cyber-bullies can now reach you in your house via your smartphone or PC. It means your home is no longer your castle in the way it once was. There is no sanctuary.
What's the answer to this?
The first is to try and develop a very thick skin.
Another is to block anyone on Twitter who is abusive.
A third is that the people who run the politics websites have to do a much better job moderating the comments they allow to be posted.
Finally, can we all calm down a bit and try to be just a tad more civil towards one another in 2013?
Would that be so very hard?