From Greek root word referring to those initiated into a secret society. Thus, this word means "known only to the initiated."
The following scriptures talk about the "mystery."
Matthew 13:10, 11, 34, 35
Romans 10:1; 11:11, 12, 19, 25, 27, 35
Romans 16:24-27
*I Corinthians 1:2, 17, 2:7, 9
I Corinthians 1:2, 3:19 - 4:1, 5
I Corinthians 15:50-57
Ephesians 1:1-4, 9, 10
Ephesians 3:3, 4, 9
Ephesians 5:30, 32
Colossians 1:23, 26-28
Colossians 1:1; 2:2-3
Colossians 3:24; 4:3-6
I Thessalonians 2:2-10
I Timothy 3:15, 16
Revelation 10:6, 7
Revelation 17:7-9, 14, 17
From foundation of world
When world began
Before the World
Before the founda-tion of the world
From beginning of world
Before all ages and generations
From foundation of world
Disciples
Jews & Gentiles
All Nations
Church of God
Church of God
Brethren/Family
Faithful in Christ
Jews & Gentiles
Members of Jesus'
Body
The Church/Saints
Saints/Faithful
Lord's Servants
Satan
House of God
Those in and not in Book of Life
Jesus
Wisdom/knowledge of God
Power/Wisdom of God
Wisdom of God
Foolish of God (greater than wisdom of man)
God's wisdom and prudence
Wisdom of God
Word of God/Wisdom
Wisdom of God
Wisdom
Lie
Godliness
God the Creator
Wisdom
Kingdom of Heaven
Complete forgiveness of sins
Grace of Lord Jesus Christ
The Cross of Christ
World, life, death, past, present, Christ ~ all belong to us
We will rise from death to immortality
We have access to riches of Christ
We are one with Christ
Christ, our hope of glory, is in us
Risen with Christ
Reward of Christ
Wicked will be destroyed
Jesus was resurrected
Mystery completed
Lamb of God shall overcome the beast
When fulness of Jews & Gentiles completed
When the Lord comes
At the last trumpet
Fulness of times when God gathers all in Christ
At the time we are presented to God
When inheritance given
The Day of Christ
Seventh (last) trumpet
When Word of God fulfilled
Wisdom mentioned 1:17, 19, 20, 21, 22, 24, 25, 26, 27, 30; Wisdom mentioned 2:1, 4, 5, 6, 7, 13
Foolishness mentioned 1:18, 20, 21, 25, 27
Foolishness mentioned 2:14