This line of scarlet thread - Joshua 2:8
It speaks of the precious blood of Christ. Scarlet is the color of Calvary. Twine it round the window through which thou lookest out on thy foes, and away to the river of death. Nothing can hurt the soul which has put the precious blood of Christ between it and condemnation or alarm. Let every outlook to the future be associated with a remembrance that His blood was shed for thee, and be thou thankful.
Rahab is the type of Gentile sinners who are permitted to share in the unsearchable riches of Christ, and to sit with Him in the heavenlies. That scarlet thread had been the means of salvation to the spies. By it they had been let down to the ground and saved from death. It must have been strong. So the blood of Christ avails, not only for us, but for all who shelter with us in the household of faith, and for others who find it the means of life as they receive it from our hands.
Let us see to it that, like Rahab, we gather father and mother, brethren and friends, to share with us the shelter and safeguard of the precious blood.
But, after all, it was not the cord that saved - that was only the emblem and type. Behind it on the one hand was God's oath, spoken through the spies, and on the other was Rahab's faith. The true safety of that house on the wall stood in the moral attitude of one woman in it. Rahab believed God who had dried up the water of the Red Sea, and who was God in heaven above and in earth beneath. This faith raised her afterward from her life of shame to become the ancestress of Christ. Such wonders does the blood of Christ work in outcasts from the commonwealth of Israel, bringing them nigh.