Does the fact that it's *different* necessarily mean that it has to alienate people or be offensive? Personally, I am indifferent to religion at large, but find it warming that people can come together and enjoy the company of their family and friends.
If people put christmas decorations up, say a nativity scene or just a big tree with lights as part of enjoying the season, that's cool with me. I don't see people celebrating their faith at this time of year, or any other, as an insult to those who are of a different belief (Or no belief at all).
Rather than deciding that because I don't go in for the Jesus thing that the nativity scene is some sort of war banner, I find it easier to just be happy for people who are happy believing that sort of thing. Same goes for any religion, any holiday (That is to say, any that I'm aware of. In the event that there is a secretive African tribe of cannibals who celebrate a religious holiday by eating their young and defecating on each other, then exclusions obviously apply).
At the end of the day I guess it comes down to the fact that I enjoy seeing people celebrating their faith and being happy. I also think people could do things which are a lot more offensive than a nativity scene, a cross displayed in public, or whatever else. When people start setting up nativity scenes inside your own home (For those who do not believe), or place of worship then there's cause for complaint, but until then I don't see the big deal.
I've neglected to vote as I don't see an option which neatly corresponds. I don't particularly believe in a God, but it's largely because I don't care one way or the other, so there's more indifference in my stance than conviction.
(Re: commercialism, I guess it just depends. My family celebrate christmas I would guess primarily out of habit, though religion doesn't come into it at all. As we have moved around and are constantly busy throughout the year doing our own thing, christmas provides a great time for us to all get back together, catch up and share the happiness. As dodgy and cliche as that sounds, that's pretty much how I see the situation, it's only as commercial as you make it, though I must admit shopping centres become a little harder to deal with at this time of year).