Not sure most people convert for such noble reasons or think one god is greater than another. IMHO, some reasons for conversion are: 1. Cold, hard cash (current Christian missionaries in India). 2. Fear of losing your head if you don't convert (more in the middle ages aka Jihad). 3. Peer pressure. If everybody around you has converted, what have you got to lose. Spanish inquisition for example. 4. Revenge or frustrated from being mistreated by previous religion authorities or higher castes. (Population of Bangladesh, perhaps recent SI converts). 5. Some miracle performed by some guru. (like AR Rahman's sister getting cured).