First of all these are not my words, it is the excerpt of speech by Quaid on Aug 11, 1947, hence you are asking this question to wrong person. In other words are you challenging Quaid that he did not know Islamic shariah and other religions?
How do you know that army is fighting with scumbags? It requires enough courage and energy to fight with regular army just for sake of ideology. It is not that easy as you have assumed. Unfortunately these scumbags have lots of support from local and non local population including indirect and moral support from JI, JuI, IK and NS.