Ephesians 5:32
This mystery is great (to musthrion touto mega estin). For the word "mystery" see Ephesians 1:9. Clearly Paul means to say that the comparison of marriage to the union of Christ and the church is the mystery. He makes that plain by the next words.
But I speak (egw de legw). "Now I mean." Cf. I Corinthians 7:29; I Corinthians 15:50.
In regard of Christ and of the church (eiv Xriston kai eis thn ekklhsian). "With reference to Christ and the church." That is all that eiv here means.
