The holiest day
Once a year, on the Day of Atonement, Israel's sins were dealt with. It was the only day the high priest went behind the veil into the Holy of Holies.
"Upon this day shall be the expiation for you, and the cleansing from all your sins: you shall be cleansed before the Lord."
Leviticus 16:30
Two goats
It started with two goats, chosen by lot:
"He shall make the two buck-goats to stand before the Lord, in the door of the tabernacle of the testimony: And casting lots upon them both, one to be offered to the Lord, and the other to be the emissary-goat."
Leviticus 16:7 to 8 ยท around 1450 BC
The first goat was killed, and its blood was carried behind the veil "for the sin of the people" (Leviticus 16:15).
The second goat was not killed. The high priest laid his hands on its head, confessed the sins of Israel over it, and it was led away alive into the wilderness (Leviticus 16:21 to 22).
One dies for the people. One goes free.
Two men
Now jump to Jerusalem, at Passover. Pilate has two prisoners in front of the crowd:
"And he had then a notorious prisoner, that was called Barabbas. They therefore being gathered together, Pilate said: Whom will you that I release to you, Barabbas, or Jesus, who is called Christ?"
Matthew 27:16 to 17
Two men brought before the people. One to be released, one to be killed. It is the Day of Atonement, played out in the street.
Son of the father
Barabbas is an Aramaic name. Bar means "son." Abba means "father."
Barabbas means "son of the father." Standing next to him was the true Son of the Father.
The crowd chose. "Then he released to them Barabbas: and having scourged Jesus, delivered him unto them to be crucified" (Matthew 27:26).
A guilty man, a murderer, walked out free. The innocent one died in his place.
Outside the camp
The sin offerings on the Day of Atonement were carried outside the camp to be burned. Hebrews makes the link:
"For the bodies of those beasts, whose blood is brought into the sanctuary for sin by the high priest, are burned without the camp. Wherefore Jesus also, that he might sanctify the people by his own blood, suffered without the gate."
Hebrews 13:11 to 12
Jesus was crucified outside the city walls.
Why this is a big deal
Every year for fifteen centuries, Israel watched two goats stand before the Lord: one killed for the sins of the people, one set free.
Then two men stood before the people. One was called son of the father, and he went free. The other was the Son of the Father, and he died for the sins of the people. Barabbas is everyone who has ever been set free by that death.