I know that some religious folk feel that they are not supposed to associate with "sinners", lest they be tempted into sin themselves. This friend of yours may be thinking along these lines, and if so, he probably doesn't even consider you as a friend anymore.
I recommend one of two courses of action at this point: cut your ties to him and write him off as lost in his religion, or continue to send him cards and gifts in an effort to shame him into realizing how silly he is acting. I favor the latter suggestion! :)
That is a horrible thing to do. A belief in friends has nothing to do with a belief in God. Friends mean more, they listen when talked to. I really do hope this person changes. You did mention them as a friend, so that does add importance to the person.
I guess he would say something like that because he's a religious nut! You can be friends with nice, normal religious people whose religion is secondary to their humanity. Religious nuts are a different story.
All anger stems from fear. If he is angry because you don't believe in God, then the deeper emotion he is feeling is fear. You can imagine the amount of pressure people like him must be under to be right. They are devoting their short lives to a fairy tale and often handing over a tenth of their income to ensure their place in a holiday resort in the sky that they will only see after they're dead. Even religious nuts realise on some level that this is nuts. So they don't want to be confronted by the possibility that they might be wasting precious time (and money).
It was unnecessary and hurtful, but also very typical. It's your choice whether to cut him out of your life or continue to be a good person and set an example to him of how decent human beings should behave. Romans 12:20 says: "Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head." Ie, if someone treats you like shit, treat them like gold and show them how much they suck until they die of embarrassment. Or something like that :)