The calling of the Gentiles into the Christian Church, so designated (Ephesians 1:9, 10; 3:8-11; Colossians 1:25-27); a truth undiscoverable except by revelation, long hid, now made manifest. The resurrection of the dead (1 Corinthians 15:51), and other doctrines which need to be explained but which cannot be fully understood by finite intelligence (Matthew 13:11; Romans 11:25; 1 Corinthians 13:2); the union between Christ and his people symbolized by the marriage union (Ephesians 5:31, 32; Comp. 6:19); the seven stars and the seven candlesticks (Revelation 1:20); and the woman clothed in scarlet (17:7), are also in this sense mysteries. The anti-Christian power working in his day is called by the apostle (2 Thessalonians 2:7) the "mystery of iniquity."

Noah Webster's New International Dictionary of the English Language

1. (n.) A profound secret; something wholly unknown, or something kept cautiously concealed, and therefore exciting curiosity or wonder; something which has not been or can not be explained; hence, specifically, that which is beyond human comprehension.

2. (n.) A kind of secret religious celebration, to which none were admitted except those who had been initiated by certain preparatory ceremonies; -- usually plural; as, the Eleusinian mysteries.

3. (n.) The consecrated elements in the Eucharist.

4. (a.) Anything artfully made difficult; an enigma.

5. (n.) A trade; a handicraft; hence, any business with which one is usually occupied.

6. (n.) A dramatic representation of a Scriptural subject, often some event in the life of Christ; a dramatic composition of this character; as, the Chester Mysteries, consisting of dramas acted by various craft associations in that city in the early part of the 14th century.