Departing from God.

The word 'apostasy' is not found in the Bible, but there are words such as 'falling away' which mean the same thing. Apostasy is described in many places, for example, 2 Thessalonians 2:1-12; 1 John 2:18-19; 4:1-3; Jude; Hebrews 2:1-4; 2 Timothy 3, etc. These verses all describe believers who are not sincere, or become tired of the gospel, listening to a more attractive message, and going back to their former worldly connections.

"But there were also false prophets among the people [Israel], just as there will be false teachers among you. They will secretly introduce destructive heresies, even denying the sovereign Lord who bought them…." (2 Peter 2:1).

Abraham
Acts of the Apostles
Adam
Adoption
Affliction
Age, Aion
Almighty God
Altar
Amen
Angel
  1. Human angels
  2. "The angels who sinned"
  3. Immortal angels
  4. "Fallen angels"
  5. "Evil angels"
Anger
Anointing
Antichrist
Apocrypha
Apostasy
Apostle
Archangel
Ark
  1. Ark constructed by Noah
  2. Ark of the Covenant
Armageddon
Ascension
Assyria
Astrology
Atonement