In his genealogy of Jesus, Matthew mentions a several women along with the male ancestors of the Messiah. One of these is a certain “Rahab” who was married to Salmon (Matt 1:5). Although it might seem intuitive to identify this woman as the Rahab of Jericho (Josh 2:1ff), there are also some good reasons to think that it may have been a different person.
One difference between Matthew’s “Rahab” and the woman of Jericho is the spelling of her name. The English spelling “Rahab” is an approximation of the Hebrew name. The Hebrew alphabet has a letter that English does not have, the letter ḥet (ח), a guttural that is pronounced at the back of the throat. It is sometimes represented in English as “ch,” pronounced something like the “ch” at the end of the German name “Bach” (the composer). A closer approximation of the Hebrew name might be “Raḥab” or “Rachab.”
But Matthew’s genealogy was written in Greek, so how does Greek deal with this name? Interestingly, the LXX (the Greek version of the Hebrew Bible), renders her name as “Hra’ab” (Gk. ῾Ρααβ), every time her name appears in the OT (Josh 2:1,3; 6:17,23,25). That is also the spelling used by James and the author of Hebrews when they refer to “Rahab the harlot” (Jas 2:25; Heb 11:31). And here is where it gets interesting–the name given by Matthew is spelled differently, “Hrachab” (Gk. ῾Ραχαβ). Is this the same name, just with a different spelling? It’s possible, but why would Matthew use a spelling that is different from the way her name is spelled in both the Greek OT and everywhere else in the NT? The chart below illustrates the unique spelling of “Rahab” in Matthew 1:5, compared to all other biblical occurrences of the name. It is also of interest to note that every other reference to her identifies her as a harlot, either directly or in the very near context. Matthew does not.
Another interesting issue has to do with chronology. The time from the Exodus to the 4th year of Solomon was 480 years (1 Kings 6:1), placing the Exodus in about 1445 BC. Allowing for 40 years in the wilderness, the two spies who met Rahab at Jericho did so in about 1405 BC. However, according to Matthew’s account, “Rahab” was the wife of Salmon, the father of Boaz, father of Obed, father of Jesse, father of King David. This same sequence of five men is mentioned in Ruth (Ruth 4:20-21) and also in the Gospel of Luke (Luke 3:31-32). If this section of genealogy has no gaps, and if the “Rahab” of Matt 1:5 is the Rahab of Jericho, then the period of time between the birth of each subsequent son was over 100 years [Boaz born to Salmon ca. 1400 BC, followed by Obed, Jesse, and then David in about 1050 BC]. Such a scenario seems difficult to accept; it seems that the two best solutions are either that the genealogy is representative (not complete) or that the woman in question was not the Rahab of Jericho.
On the other side of the coin we have two arguments that would seem to favor the “Rahab” of Matt 1:5 as being the harlot of Jericho. The first is that one could conceivably translate the Hebrew “Rahab” (Heb. רָחָב) as it appears in Matthew (Gk. ῾Ραχαβ). In fact, one might argue that this would be a more intuitive way to render it in Greek, despite the fact that the translators of the LXX did not do so (nor the other NT authors). Secondly, it seems odd that Matthew would make mention of a woman in the genealogy of Jesus who is otherwise unknown. What purpose would such a person serve in the genealogy? Here we are dealing more with literary purpose and authorial intent, which can be a slippery subject. The two other women mentioned in the genealogy of Matthew are Tamar, who posed as a prostitute (Gen 38:15), and the wife of Uriah (i.e., Bathsheba), whom one might argue David treated like a prostitute. However, this sort of reasoning is quite subjective, and may not be at all what Matthew had in mind as he wrote.
To summarize, it seems possible that the “Rahab” of Matthew 1:5 was the harlot of Jericho, but that identity can hardly be considered certain.