There are lots of apostate people. Ever since the time of Judas, there have been people who profess faith in Christ and identify themselves as disciples but who never genuinely embrace the truth. They may understand the truth. They may even seem to follow it enthusiastically for a while. They might identify with a church and therefore become an active and integral part of the earthly Christian community. Sometimes they even become leaders in a church. But they never really believe the truth with an undivided heart. Like tares among the wheat, they have an appearance of authenticity for a while, but they are incapable of producing and useful fruit (Matthew 13:24-30).

– John MacArthur