As student of history, I can name numerous cases of Christians converting to Islam. I can recall no instance where Muslims converted to Christianity in any appreciable numbers. I think the reason is Christians don’t murder other Christians who leave the the faith. But of all Muslim sects, the Wahhabis are the mostaggresive, intolerant and radical. ISIS is their son, like al Quaida is.
Moslem converts to Christianity — there were effective cases when the Byzantine empire reconquered Syria and Anatolia in the 9th century