Is Christmas at all contrary to world peace? That seems unlikely, but there are certainly good arguments for the idea that Christianity is a hinderance to world peace. Christians celebrate Christmas as the date of the birth of their savior, the focal point of their religion. In a sense, then, while Christmas is a date for Christians to celebrate the start of their religion, it may also be a date for non-Christians to mourn the loss to peace for the entire world. It's a sad day to have to commemorate, especially since so many other people are celebrating, but it's still something that is worth remembering and thinking about.
Perhaps it seems extreme to even suggest boycotting Christmas in reaction to the violence and horror committed around the world in the name of Christianity, but then again maybe not. Accepting and participating in Christmas, even when one is not a Christian, gives the appearance of accepting the preeminent position of Christianity in American culture. This, in turn, helps give the impression that Christianity really isn't so bad after all. It may thus be reasonably argued that boycotting Christmas could become an effective means both for bringing attention to all these problems as well as to the ways in which Christianity works to dominate the culture through holidays like Christmas.
Christians don't always seem to realize just how much hostility and animus they have engendered all around the world by their behavior. When it's pointed out to them, they frequently go into denial, insisting that they haven't done anything wrong and/or anyone who does do anything wrong isn't a "real" Christian in the first place. Boycotts may serve to reinforce the message to the point where it's no longer possible to ignore it.
This image is based on a World War I poster promoting peace and discouraging war.