Romanos 10:9

If thou shalt confess

(εαν ομολογησηις). Third class condition (εαν and first aorist active subjunctive of ομολογεω).With thy mouth Jesus as Lord

(εν τω στοματ σου Κυριον Ιησουν). This is the reading of nearly all the MSS. But B 71 Clem of Alex. read το ρημα εν τω στοματ σου οτ Κυριος Ιησους (the word in thy mouth that Jesus is Lord). The idea is the same, the confession of Jesus as Lord as in 1 Corintios 12:3; Filipenses 2:11.

No Jew would do this who had not really trusted Christ, for Κυριος in the LXX is used of God. No Gentile would do it who had not ceased worshipping the emperor as Κυριος. The word Κυριος was and is the touchstone of faith.And shalt believe

(κα πιστευσηις). Same construction. Faith precedes confession, of course.