the calling of the Gentiles into the Christian Church, so designated ( Ephesians 1:9 Ephesians 1:10 ; 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 Ephesians 5:32 ; 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."

These dictionary topics are from
M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition,
published by Thomas Nelson, 1897. Public Domain, copy freely.