Rahab the harlot represents the true nature of the wandering and unfaithful human heart; her survival of the judgment executed against Jericho is also representative of that remnant part of the human heart (that outer-rind part) which endures the fires of judgment, that purged and purified portion which is now the representation of the whole in its much smaller size (having had much of the whole killed and dropped out of its outer-rind sheath).
Spiritually implied is the natural antithesis of what quick discernment is as made by the unregenerated conscience or unconverted heart: presumption. The idea of a breathing dead thing is the paradoxical dilemma we are confronted with in our study of Jericho, and particularly what it means to us symbolically and spiritually. Moonshine and lunacy derive their types of madness from trying to live by secondary lights, the dictates of their own dead hearts and mismanaged/misinformed minds; it is like, or rather leads to, the torment Isaiah the prophet said would occur to those who tried to live by the light of their own making. Here is exactly what Isaiah said:
Who is among you who [reverently] fears the Lord, who obeys the voice of His Servant, yet who walks in darkness and deep trouble and has no shining splendor [in his heart]? Let him rely on, trust in, and be confident in the name of the Lord, and let him lean upon and be supported by his God. Behold, all you [enemies of your own selves] who attempt to kindle your own fires [and work out your own plans of salvation], who surround and gird yourselves with momentary sparks, darts, and firebrands that you set aflame!—walk by the light of your self-made fire and of the sparks that you have kindled [for yourself, if you will]! But this shall you have from My hand: you shall lie down in grief and in torment. (Isaiah 50:10-11, Amplified Bible).
Before the work of redemption, God describes the human heart as “deceitful above all things, and it is exceedingly perverse and corrupt and severely, mortally sick! Who can know it [perceive, understand, be acquainted with his own heart and mind]?” (Jeremiah 17:9, Amp.). This is that dead moon, that false-promising odor, and that warped conscience factor; this is all the negative side of what Jericho means to us (and remains to us until regeneration).
There is a positive side, however, a regeneration, a restoration of a fine bouquet, and a clear message from a loving and saving God. It is Rahab the harlot, and all her house which is saved by a red thread, and because she allowed God to look in on her, to spy on her (she allowed herself to be scrutinized) and therefore she was spared (saved).
She, born of the father, born of incest, from the corrupted lineage of Lot, an Ammonite, not only gets saved from destruction in Jericho, but gets inserted back into a pure lineage, a lineage which eventually produces the Savior of all mankind, Jesus Christ our Lord. This is the destiny of all that receive God’s angels, emissaries, spies, those that allow themselves to be pre-judged by the scrutiny of God before the full-scale and final judgment; salvation is premised upon the sure ground of repentance (to change one’s mind and attitude; to switch sides from the enemy’s camp to God’s camp; to change loyalties).