The term 'CHRISTIAN MESSENGER' can be broken down into two words, 'CHRISTIAN' and 'MESSENGER'. The word 'CHRISTIAN' refers to a person who follows the teachings of Jesus Christ and is a member of the CHRISTIAN faith. The word 'MESSENGER' refers to someone who delivers a message or information from one person to another. In the context of the crossword puzzle, the answer to the clue 'APOSTLE' (7 letters) is 'CHRISTIAN MESSENGER', as an APOSTLE is someone who is sent out to spread the message of Christianity.