What is a mystery in Scripture? A mystery in Scripture means that God is revealing something, that up to that time, He had not revealed. There are two elements which always enter into a New Testament mystery: 1. It cannot be discovered by man, for it is always a revelation from God; and 2. it is revealed at the right time and not concealed, and enough is revealed to establish the fact without all the details being disclosed.
There are fifteen mysteries in the New Testament:
1. The mysteries of the Kingdom of Heaven (Mat.13:3-50; Mk.4:11; Lk.8:10).
2. The mystery of His will (Eph.1:9).
3. The great mystery of Christ and His church (Eph. 5:32; Col.4:3).
4. The mystery of the Gospel (Eph.6:19).
5. The mystery of Israel’s blindness during this age (Rom.11:25).
6. The mystery of the faith (1 Tim.3:9).
7. The mystery of the translation of living saints at the end of this age (1 Cor.15:51-52; 1 Thes.4:13-17).
8. The mystery of the N.T. Church as one body composed of Jews and Gentiles (Eph.3:1-12; 6:19; Rom.16:25; Col.4:3).
9. The mystery of the Church as the bride of Christ  (Eph.5:23-32).
10. The mystery of being in Christ (Gal.2:20; Col.1:26-27).
11.  The mystery of Christ as the incarnate fullness of the Godhead embodied, in whom all the divine wisdom for man subsists (1 Cor.2:7; Col.2:2,9).
12. The mystery of godliness (1 Tim.3:16).
13. The mystery of iniquity (2 Thes.2:7; Mat.13:33).
14. The mystery of the seven stars (Rev.1:20).
15. The mystery of the woman (Rev.17:5,7).
God has NOT revealed everything to us. There are many things God has NOT told us, because it is not necessary for us to know! When it is necessary, He will reveal them to us! Praise His Holy Name!