"Take heed brethren, lest there be in any of you an EVIL heart of UNBELIEF, in DEPARTING from the living God." ( Hebrews 3:12 )
"If any man LOVE NOT the Lord Jesus Christ, let him be ANATHEMA Maranatha." ( 1 Corinthians 16:22 )
"For many walk, of whom I have told you often, and now tell you even weeping, that they are the enemies of the cross of Christ: Whose end is DESTRUCTION, whose God is their belly, and whose glory is their shame, who mind earthly things." ( Philippians 3:19 )
These verses reveal the contempt in which the NT holds those who abandon Christianity, viewing them as evil, cursed, and awaiting execution.