In place of and said, Good News Translation has “And God said.” Most readers will immediately recognize that the same being is referred to in both verses 4 and 5; for others it may be necessary to have either “the Creator … He” or “God … He.” It is important for verses 4 and 5 to flow together smoothly and naturally. If translators use a phrase such as “God’s word” in verse 4, for example, then here they may wish to say “God also said” or “And he said” (Barclay). Note that no matter how this is structured, it must not seem that Jesus is the subject of said.
For this reason … shall become one flesh is a quotation from Genesis 2.24. In the Genesis narrative the phrase For this reason is important, because it serves to connect verse 24 of Genesis 2 with verse 23 and to explain it. However, in the present context it serves no obvious function. Nevertheless most translators retain the phrase, since it was part of the quotation Jesus gave (see, for example, Good News Translation). The problem for some is that the phrase does not refer to anything in the immediate context and consequently poses problems to the readers. Many translators will have a footnote showing the reference to the Genesis passage, or even a note such as “In God’s word, that was what the first man said when God created woman as his companion.” Other translators have provided sufficient context by structuring verses 4 and 5 together, as for example “Surely you have read in God’s word about how God created mankind? He made both male and female, and that is why it also says, ‘For this reason a man … one flesh.’ ”
Be joined to translates a verb which may be used of sexual union (see 1 Cor 6.16) but may also be used of any type of close association. Barclay translates “joined inseparably to”; New English Bible has “be made one with”; Die Bibel im heutigen Deutsch translates “live with.”
And the two shall become one flesh, a formal rendering of the Greek text, is representative of what most other translations have done. Slightly different are Jerusalem Bible (“and the two become one body”) and Bibel im heutigen Deutsch, 1st edition (“The two are then one body”), while Good News Translation: (“and the two will become one”) and New American Bible (“and the two shall become as one”) make significant departures from a formal transfer. Barclay combines be joined to … shall become one flesh into a single statement: “and will be joined inseparably to his wife.” The restructuring of Good News Translation and New American Bible, though perhaps satisfactory for some levels of English readers, will be entirely unsatisfactory in a number of other languages. Readers will ask “Become one what?” All in all, it may be best to translate “will be like one body” or “… like one person.”
Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .