Most Christian churches see baptism as a once-in-a-lifetime event that can be neither repeated nor undone. They hold that those who have been baptized remain baptized, even if they renounce the Christian faith by adopting a non-Christian religion or by rejecting religion entirely. But some other organizations and individuals are practicing debaptism. Using a hair dryer, some atheist groups have conducted tongue-in-cheek "debaptism" ceremonies, not intended to be taken seriously.