Not all Muslim's converting to Christianity will be faking it. The fastest growing Christian church is
Iran, and Afghanistan coming second. Other reports give different figures but the Christian faith is growing in nations where to be a Christian is definitely not an advantage and so to claim to have converted is not something done lightly.
So, while there maybe some claiming to convert to ease their application to immigrate not all will do so, and for some even to claim the change could lead to loss of friendships and community and likely greater trouble for family remaining "at home".