Or, there is another possibility. There could be a lot of people converting to Christianity.
I think any number of Muslim converts to Christianity are an UNDER-representation. If your neighbors and even family think they should kill you for converting, you don’t tell a pollster you now believe in Jesus.
And where is the anger at Muslims OVER-reporting their numbers, often claiming that all Middle Eastern and arab immigrants in a nation are Muslim, when many US Arab and Mideast immigrants are Christian. (Lebanese Christians, iranian jews, Coptic Christians)