The Haftorah Parshas Korach is all about Shmuel HaNavi. In Parshas Korach, Moshe justifies himself that he acted purely without Negi'os. In the Haftorah, we have Shmuel HaNavi justifying himself in almost identical words! The story of Korach is a major tragedy, how Korach remains a Baal Machlokes in Gehinom; a person who fell because of Negi'os.
Moshe represents the extreme opposite; a totally pure and selfless person without Negi'os. Perhaps this Haftorah is chosen as a consolation for Korach, that in the end he is also Zoche to have purity without Negi'os [at least through his descendant]. This shows Hashem’s extreme Rachmanus, even for those people who failed to keep His will.
When Shaul HaMelech failed, he was told that his Malchus would be given away to Dovid. Chazal say that Hashem would someday appease the pain of Shaul, and when Vashti lost her Malchus, it was given to Esther, who was Shaul’s descendant. How much Chizuk we get when we see how much love Hashem has for those who fail. We realize how He never forgets their pain, and gives them new opportunities.
Just as this Haftorah is an example of a positive ending from a disastrous beginning, similarly in last week’s Haftorah we have the story of the two Meraglim [Kalev and Pinchos]. That story is loaded with a Gevaldige Mussar Haskel, how Hashem makes sure to give people a second chance, and how by doing Teshuva, the worst can become our greatest heroes.
Rachav HaZonah had sinned for 40 years. If Rachav HaZonah can do Teshuva, and marry the Gadol HaDor (Yehoshua!), anyone can do Teshuva! If you just admit your sins [symbolized by a hanging “red” string] and you want to change, then there is hope and eventually a Yeshua.