The church is said to be a mystery according to Colossians 1:25, 26 "Whereof I am made a minister, according to the dispensation of God which is given to me for you, to fulfill the word of God, Even the mystery which hath been hidden from ages and from generations, but now is made manifest to his saints:" What is this Mystery - this is something that was hidden in the past during the Old Testament period but now in the New Testament it is revealed to us. This mystery is that the Gentiles should be partakers with the Jews in the gospel and be in the same church. This Book Teaches Everything a Believer of Christ should know about Church the Ekklesia.