A lot of True Believing Mormons (TBM's) believe that people who no longer believe the Church is true should leave. I left immediately upon no longer believing, but there are a lot of New Order Mormons (NOM's) who no longer believe, but stay anyway for family, community, moral upbringing for their children, the feeling of elevation (AKA the Spirit), or because it is the best thing out there. I do not think that it is our place to judge, but to be understanding and let each person live according to the dictates of their own conscience as the 11th Article of Faith says.
Here are two links. The first was my short struggle about whether I would fake belief at least through my son's naming blessing. I have an advantage that most newly non-believers don't have, my wife is receptive to the idea that the Church is not true.
The second is a link to the home of New Order Mormons: http://forum.newordermormon.org/index.php