1 John 2:19 They went out from us, but they did not really belong to us. For if they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us.
1 John 2:19 They went out from us, but they did not really belong to us. For if they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us.
>> Has to be reconciled with this, which suggests a person could have been a true believer and repented of their faith:
Hebrews 6:4-6 (NLT)
4 For it is impossible to bring back to repentance those who were once enlightened—those who have experienced the good things of heaven and shared in the Holy Spirit, 5 who have tasted the goodness of the word of God and the power of the age to come— 6 and who then turn away from God. It is impossible to bring such people back to repentance; by rejecting the Son of God, they themselves are nailing him to the cross once again and holding him up to public shame.