What makes you think the Government will stop at banning Islam????
Because there is no reason to ban Christianity, plus it's constitutionaly protected while Islam is not.
One would hope, that if the time came when the government DID have the guts to purge Islamic evil from this land, it would be because ther were enough Christian minded people elected to government.
But no worries, as I said, This country is going to go down because of it's ignorance, just like the roman empire did, just like (what is now Greece) fell to Islam.