Here is a great Keynote Theme for any presentations you need to make with a Christmas theme. It avoids any religious connotations without losing your point of the season. This Theme will really help you to get your point across while giving your audience something very pretty to look at.
I found this picture at Desktop Wallpaper HD. They have a lot of cool designs to use for Keynote themes.
Simply add another slide and use the background image fill to get another slide with the background.