The House On The Wall That Could Not Fall

20 So the people shouted when the priests blew with the trumpets: and it came to pass, when the people heard the sound of the trumpet, and the people shouted with a great shout, that the wall fell down flat, so that the people went up into the city, every man straight before him, and they took the city.

Rahab's house could not fall:
It was an object of Grace.
It was protected by the Blood of Christ
It was protected by Faith
It was protected by the promise of God
It was protected by staying IN the house.