[pinkpanther]

That depends. 

Are we permitted to lie to advance or propagate our religion? The answer is no.

Good lie my friend!

There are several forms of lying to non-believers that are permitted under certain circumstances, the best known being taqiyya (the Shia name).  These circumstances are typically those that advance the cause of Islam - in some cases by gaining the trust of non-believers in order to draw out their vulnerability and defeat them.