The crescent and star are signs established in paganism and are not representative of Islam in any way at all. Given its pagan origins, consider what that means when you prostrate on a mat that has this symbol on it, or when you pray in a mosque that is decorated with it as its highest symbols. This is a woeful innovation that can lead to nothing but hypocrisy.
(Source: http://www.ghazalaa.tumblr.com)