Puritan heretic William Gurnall writes concerning how few the “mystery of the gospel” is revealed to in Ephesians 6:19.
“It is a mystery in regard of the paucity of those to whom it is revealed. Secrets are whispered into the ears of a few, and not exposed to all. ‘Unto you it is given to know the mystery of the kingdom of God,’ Mark 4:11. Who were those ‘you,’ but a few disciples who believed on his name? The greater part of the world were ever strangers to this mystery. Before Christ’s time it was impaled within a little spot of ground of the Jewish nation. Since it came abroad into the Gentile world, and hath been travelling [sic] above these sixteen hundred years hither and thither, how few at this day are acquainted with it! Indeed, where its glorious light shines long, many get a literal notional knowledge of it — it were strange that men should walk long in the sun and not have their faces a little tanned with it; but the spiritual and saving knowledge of this mystery is revealed but to few, for the number of saints is not great compared with the reprobate world.” (William Gurnall, The Christian In Complete Armour)