It is explicitly said in their holy texts (I forget which one) that
"If you cannot defeat them by the sword? Move in, make babies & outnumber them until the nation welcomes Islam."

They are also ordered to NOT assimilate, but to maintain Islam in their homes & convert anyone they can.
Of course they're allowed to lie to the infidel. Also rob from them, rape them and kill them too if they can get away with it.