The Bible mentions a scarlet thread in several different contexts, from an unusual childbirth to the high priestly garments to the conquest of Canaan.
One reference to the scarlet thread in the Bible occurs during the birth of the twin sons of Judah and Tamar (Genesis 38:27–30). As Tamar was giving birth, the arm of one twin, Zerah, reached out of the birth canal, and immediately the midwife tied a scarlet thread to the baby’s wrist to designate Zerah as the firstborn. As it turned out, however, Zerah was not the firstborn; the arm was withdrawn into the womb, and the other twin, Perez, was born first.
In the case of Perez and Zerah, the scarlet thread was to indicate who was to have the designation and privileges of the firstborn. To all appearances, Zerah seemed to be the one, but God had different plans, and Perez was the firstborn. In God’s providence, it was through Perez that the line of the Lord Jesus Christ proceeded (Matthew 1:3).
The Bible also mentions scarlet thread or scarlet yarn as part of the tabernacle’s curtains (Exodus 26:1) and the high priest’s ephod (Exodus 28:6), along with threads of gold, blue, and purple. Scripture does not comment on the significance of those colors in the curtains or ephod, but some commentators surmise that the gold, blue, and purple foreshadow Christ’s glory, heavenly origin, and kingly position, while the scarlet thread represents Christ’s atoning work on the cross through the shedding of His blood.
Another significant mention of scarlet thread is in Joshua 2. Two spies had been sent to Jericho in advance of the Israelites’ taking of that city. The spies were hidden in Jericho by Rahab the harlot, who expressed her faith in Israel’s God and protected the spies (see Hebrews 11:31). Rahab allowed the Hebrew spies to escape from Jericho by letting them down through her window by means of a rope made of scarlet thread. As they departed, the spies told Rahab, “Tie this cord of scarlet thread in the window” (Joshua 2:18), with the promise that she and her household would be kept safe in the coming invasion. By faith, Rahab obeyed: “And she tied the scarlet cord in the window” (verse 21).
Later, when the walls of Jericho fell down and the Israelites took the city, Joshua commanded that Rahab and her family be spared (Joshua 6:22–23). Marking her home was, of course, the “cord of scarlet thread.” It’s easy to dismiss the color of Rahab’s rope as mere coincidence, but the scarlet color is significant. The rope in her window was a sign of her faith and led to her salvation, as she was not destroyed with the rest of Jericho. The scarlet rope—the color of blood—worked for Rahab much as the blood of the Passover lamb had worked during the exodus: every home marked with blood was spared death that night (Exodus 12:13). God’s mercy and forgiveness of Rahab the harlot was signified by a rope of scarlet thread, which becomes a symbol of the blood of Christ.
Theologians and Bible students sometimes refer to “the scarlet thread running through the Bible.” By this they mean that the Bible’s theme is Jesus Christ and His sacrifice for the redemption of mankind. The blood of Christ runs throughout the entire Bible, symbolically. It is seen in the animals killed in Eden to provide garments for Adam and Eve, the ram that took Isaac’s place on the altar of Moriah, the Passover lamb, the institution of the sacrificial system, the scarlet rope of Rahab, and the thousands of years of sacrifices performed at the tabernacle and temple. The scarlet thread runs all the way up to John the Baptist’s declaration, “Look, the Lamb of God, who takes away the sin of the world!” (John 1:29) and to the foot of the cross, where Jesus finally says, “It is finished” (John 19:30).
“Without the shedding of blood there is no forgiveness” (Hebrews 9:22), and that’s why the symbolism of the scarlet thread in the Bible is significant. The scarlet thread is the theme of atonement found throughout the pages of Scripture.