Identifying Babylon

Fallen, fallen is Babylon the Great 

(Revelation 14:8)

Here are just three of the reasons I would identify Babylon as Jerusalem and not Rome: 

1. Jerusalem has already been in view and identified in Revelation 'figuratively' in terms of Old Testament enemies of God: 

Revelation 11:8 Their bodies will lie in the street of the great city, which is figuratively called Sodom and Egypt, where also their Lord was crucified. 

2. In Revelation 17:1-7 we are shown a Harlot-City called 'Babylon the Great' who resembles the original Babylon (sitting on many waters: cf. Jeremiah 50-51) and who has committed fornication with the kings of the earth.
Huh. That all sounds pretty pagan to me ... must mean Rome then? Except for the fact that Jerusalem and Israel are spoken of very often in these terms by the prophets:

Isaiah 1:21 See how the faithful city has become a harlot! She once was full of justice; righteousness used to dwell in her--but now murderers! 

Jeremiah 2-3

Ezekiel 16

Ezekiel 23

Hosea 9:1 Do not rejoice, O Israel; do not be jubilant like the other nations. For you have been unfaithful to your God; you love the wages of a prostitute at every threshing-floor.

And as I was reminded of in preaching through John 18-19 last week, the chief priests pledge allegiance to Caesar over God's anointed King Jesus:

John 19:14-15 It was the day of Preparation of Passover Week, about the sixth hour. "Here is your king," Pilate said to the Jews. 15 But they shouted, "Take him away! Take him away! Crucify him!" "Shall I crucify your king?" Pilate asked. "We have no king but Caesar," the chief priests answered.

 3. This view is corroborated via 1 Peter 5:13 

She who is in Babylon, chosen together with you, sends you her greetings, and so does my son Mark.

Peter's home & ministry were in Jerusalem

Acts 8:1 And Saul was there, giving approval to his death. On that day a great persecution broke out against the church at Jerusalem, and all except the apostles were scattered throughout Judea and Samaria.

 Acts 12:1-3  It was about this time that King Herod arrested some who belonged to the church, intending to persecute them.  ² He had James, the brother of John, put to death with the sword.  ³ When he saw that this pleased the Jews, he proceeded to seize Peter also. This happened during the Feast of Unleavened Bread.

Galatians 1:18  Then after three years, I went up to Jerusalem to get acquainted with Peter and stayed with him fifteen days.

Galatians 2:1-9  Fourteen years later I went up again to Jerusalem, this time with Barnabas. I took Titus along also.  ² I went in response to a revelation and set before them the gospel that I preach among the Gentiles. But I did this privately to those who seemed to be leaders, for fear that I was running or had run my race in vain.  ³ Yet not even Titus, who was with me, was compelled to be circumcised, even though he was a Greek.  ⁴ This matter arose because some false brothers had infiltrated our ranks to spy on the freedom we have in Christ Jesus and to make us slaves.  ⁵ We did not give in to them for a moment, so that the truth of the gospel might remain with you.  ⁶ As for those who seemed to be important--whatever they were makes no difference to me; God does not judge by external appearance--those men added nothing to my message.  ⁷ On the contrary, they saw that I had been entrusted with the task of preaching the gospel to the Gentiles,  just as Peter had been to the Jews. ⁸ For God, who was at work in the ministry of Peter as an apostle to the Jews, was also at work in my ministry as an apostle to the Gentiles.  ⁹ James, Peter and John, those reputed to be pillars, gave me and Barnabas the right hand of fellowship when they recognised the grace given to me. They agreed that we should go to the Gentiles, and they to the Jews.

AND this was also the case for Mark & Silas [cf. 1 Peter 5:12-13]

Acts 12:12    When this had dawned on him, he went to the house of Mary the mother of John, also called Mark, where many people had gathered and were praying.

Acts 15:22-40  Then the apostles and elders, with the whole church, decided to choose some of their own men and send them to Antioch with Paul and Barnabas. They chose Judas (called Barsabbas) and Silas, two men who were leaders among the brothers.  ²³ With them they sent the following letter: The apostles and elders, your brothers, To the Gentile believers in Antioch, Syria and Cilicia: Greetings.  ²⁴ We have heard that some went out from us without our authorisation and disturbed you, troubling your minds by what they said.  ²⁵ So we all agreed to choose some men and send them to you with our dear friends Barnabas and Paul--  ²⁶ men who have risked their lives for the name of our Lord Jesus Christ.  ²⁷ Therefore we are sending Judas and Silas to confirm by word of mouth what we are writing.  ²⁸ It seemed good to the Holy Spirit and to us not to burden you with anything beyond the following requirements:  ²⁹ You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality. You will do well to avoid these things. Farewell.  ³⁰ The men were sent off and went down to Antioch, where they gathered the church together and delivered the letter.  ³¹ The people read it and were glad for its encouraging message.  ³² Judas and Silas, who themselves were prophets, said much to encourage and strengthen the brothers.  ³³ After spending some time there, they were sent off by the brothers with the blessing of peace to return to those who had sent them.  ³⁴ {Some manuscripts them, 34 but Silas decided to remain there}  ³⁵ But Paul and Barnabas remained in Antioch, where they and many others taught and preached the word of the Lord.  ³⁶ Some time later Paul said to Barnabas, "Let us go back and visit the brothers in all the towns where we preached the word of the Lord and see how they are doing."  ³⁷ Barnabas wanted to take John, also called Mark, with them,  ³⁸ but Paul did not think it wise to take him, because he had deserted them in Pamphylia and had not continued with them in the work.  ³⁹ They had such a sharp disagreement that they parted company. Barnabas took Mark and sailed for Cyprus,  ⁴⁰ but Paul chose Silas and left, commended by the brothers to the grace of the Lord.