Originally posted by sonhouse
You have to assume they are serious, they are burning their religious bridges behind them.
To go back to where they came from would be certain death because of Apostasy.
It's untrue that a Muslim who converts to another religion cannot then return to Islam.
"7057: How does an apostate come back to Islam"
"His repentance will be accepted until the point the death-rattle sounds in his throat and his soul departs.
If he is guided back to Islam within the time it is possible (before death) and he performs
as many of the Islamic duties as he can, then he is a Muslim."