1. It is the Greek word musterion from meuo which meant "to initiate into (the mysteries)," i.e., to make known special secrets.
2. Musterion means a secret, rite, or teaching which the initiate knows but no one else knows.
It refers to God's secrets, His counsels and purposes which are not known to man apart from His special revelation in Scripture or by his prophets (Dan. 2:18-23; 27-30).
In most cases in the New Testament it refers to church truth which was not known in Old Testament times, but has become revealed in the New Testament (cf. Eph. 3:1-9). The Old Testament revealed the death and resurrection of Jesus Christ and the salvation of the Gentiles, etc., but there was no mention of the church and certain aspects of the church age. These things were mysteries (Rom. 16: 25-26).
It is also used of spiritual-truth revealed in Scripture, Old or New Testament truth, but which remains a secret, veiled truth to the unbeliever because he cannot fathom or spiritually understand it. It refers to truth which man cannot comprehend by experience, trial and error, testing, or by his own reason or human philosophy (1 Cor. 2:6 -14; Mark 4:11). Through the Word of God, the new nature and the ministry of the Holy Spirit, the believer becomes the initiate of God's mysteries (cf. Phil. 4:12 where Paul uses the Greek word mueo). For this more general use, compare also 1 Cor. 4:1 and perhaps Eph. 6:19; Col. 4:3; and 1 Tim. 3:9.
1. The mystery of the kingdom of heaven (Matt. 13). The mystery of the interim program of God between Christ's first and second advents.
2. The mystery of the blindness of Israel and God's purpose with Israel's blindness (Rom. 11:1-25).
4. The mystery of the church as the body of Christ where Jew and Gentile become one new man in Christ (Eph. 3:1-11; 2:11f).
5. The mystery of the church as the bride of Christ (Eph. 5:25-32).
6. The mystery of the indwelling of Christ as the hope of glory or spiritual deliverance by the power of the indwelling Christ (Col. 1:26-27; 2:2).
7. The mystery of lawlessness--the continuation and gradual build up of the state of lawlessness which will culminate in the man of lawlessness (I Thess. 2:7).
8. The mystery of godliness, or the process by which man becomes God-like in character through the person, work and life of Jesus Christ as He is faithfully proclaimed and defended by the church of Jesus Christ (I Tim. 3:16).
9. The mystery of the church as the seven stars (Rev. 1:20).
10. The mystery of God, the answer to the age old question, why has God allowed Satan and evil to continue to exist (Rev. 10:7).
11. Please note that the answer to this is found in Scripture, it was preached to God's prophets. There are two key parts to this answer: (a) To resolve the angelic warfare, to answer and demonstrate that Satan, the accuser and slanderer of God's character is wrong in his accusations and that he is worthy of God's judgment for his sin. (b) To demonstrate God's patience and love, and to provide ample opportunity for men to come to Christ (2 Pet. 3:7-8).
12. So when the angel of Revelation 10:7 says "time shall be no more" he means that once the seventh trumpet is sounded, this time of demonstrating God's character and of demonstrating man and Satan for what they are, this time of allowing Satan and rebellion to continue, will be over; God will act swiftly now to establish His rule of righteousness on earth. This period of the patience of God is over.
13. The mystery of Babylon, the truth regarding the source of the ancient and godless mother-child cult (Rev. 17:5, 7).