There is more than one person who disagrees with you; are you saying that all of them are liars?
Whether or not Bush finds WMDs in Iraq (and I believe the stockpiles of "pesticide" at ammo dumps probably qualifies), did he lie about it? I don't think so. I think he was operating on good information that will eventually prove to be right. But even if it doesn't, that doesn't make him a liar. Just incorrect.
Again as a side note, I've long maintained that WMDs are an unnecessary condition to do what we did in Iraq in a post 9/11 age. I don't care if there never were WMDs there as long as no one lied about it to gain support. We know for a fact that Saddam funded terrorists. Maybe not al queda (but maybe!), but certainly the sorts of people who would look to destroy us utterly using the same means as those who attacked us in 2001.