How do you handle a response about a holiday greeting?

Over the weekend I worked for a friend of mine who runs a nice handmade items shop. Because the weekend after Thanksgiving is one of her busiest I worked for her on Sat. & Sun. by greeting her customers ping out Cocoa. I was to tell clients Merry Christmas or whatever to them when they came in. I had a couple that got offended. I asked them what their religious affiliation was and corrected to appease. But, when several of my Pagan and Wiccan friends came in I greeted them with Happy Yule and Candlemas. Some friends I knew were Athiests and greeted them with Happy Holidays or Merry festivus. But I got chewed out by one person that was offended by just the general holiday greetings, asked if he had a religious affiliation and apologized when he said NO very loudly. Then I told him have a wonderful day and enjoy the shop. As he and his wife left he said that it was very inconsiderate of me to say such things to people I did not know. I explained it to him like this...............