Is Islam The Fastest Growing Religion?

The view that Islam is the world's fastest growing religion is considered by many Muslims to be proof Islam is true. Weather one believe such a claim or not the reasons behind what is causing such growth can shed light onto what the religion of Islam is offering the world. If the reasons behind Islam's growth are noble than Islam could be considered something good for people & society but if the reasons for growth are immoral how can Islam be a true moral guide for any society or person?