What does the Bible mean when it says, “Come Out Of Her My People?”
We are told to come out of the world (Rev 18:4), but the world doesn’t easily come out of us! We can be like Lot’s wife and look back. Our flesh is constantly pulling us back to the world, but we know we have to leave the world, while still living in the world, but the natural man has a desire to return to Sodom. A good indication that we’re coming out of the world while still having to live in the world is that we’ve got some God-haters. Jesus said, “If you were of the world, the world would love you as its own; but because you are not of the world, but I chose you out of the world, therefore the world hates you” (John 15:19). If we hate the world’s system, the world will hate us. It’s just that simple. We are either for Christ or against Him, and the world is against Him for sure. 
Come Out, Israel
Just like God called Israel out of Egypt, He has called us out of the world (John 6:44). Egypt represents being under the bondage of sin, and just as we could not escape the world without God’s help, they could not escape their Egyptian task masters without God’s strong arm. They needed help and God was the One Who provided it as He rescued them from Pharaoh and Pharaoh’s army. God brought them from slavery to freedom. We too were called out of slavery as we were slaves to sin, being under the bondage of sin (Rom 6:15). We were brought to repent of our sins; to leave them and forsake them and turn to God, but like Israel, we needed God’s help. Thankfully, salvation is fully a work of God (Acts 4:12; Eph 2:8-9), meaning He enables us to come out of this world and to repent of our sins (Acts 5:31, 11:18; 2 Tim 2:24-26). Of course we’ll never be sinless this side of heaven, but we should be sinning less over time. That’s a sign that we’re coming out of this world instead of going into it. When the Israelites began to grumble in the Wilderness, they began to think about Egypt again…lusting after the old ways and the old things, perhaps even the old customs. They wanted to go back into the world.
Come Out of Her
After the fall of Babylon, the second and final time (Rev 18:2), the Apostle John records “another voice from heaven saying, “Come out of her, my people, lest you take part in her sins, lest you share in her plagues” (Rev 18:4). God is warning them, and I believe He is warning us, to come out of this world. Satan is the god of this world and its detestable system (2 Cor 4:4). The voice from heaven reminds them that they risk sharing in the sins of the world if they do not come out of Babylon, which is symbolic of the world and all the false religions. The voice from heaven warns, otherwise “you share in her plagues; for her sins are heaped high as heaven, and God has remembered her iniquities” (Rev 18:5).
The New Temple
In ancient times, God came down from heaven and dwelt in the Temple and His people came to minister to Him. Today, God comes down from heaven and lives within the people and He ministers to them. We are the temple of God…the temple where the Holy Spirit lives, so imagine if we continually desecrated the temple, but that’s what we can do by destroying the temple of God (our bodies). Our temple can be destroyed by drugs, alcohol, untreated depression, overindulgence, and any number of things, but this must grieve the Holy Spirit Who has to endure such sin. The Apostle Paul said that “we are the temple of the living God; as God said, “I will make my dwelling among them and walk among them, and I will be their God, and they shall be my people” (2 Cor 6:16). Since God is dwelling in us we must “go out from their midst, and be separate from them, says the Lord, and touch no unclean thing; then I will welcome you” (2 Cor 6:17). If that happens, God says, “I will be a father to you, and you shall be sons and daughters to me, says the Lord Almighty” (2 Cor 6:17-18).
A rich man who had been blessed by God kept accumulating wealth until he thought, I “have plenty of good things laid up for many years. Take it easy. Eat, drink, and be merry” (Luke 12:19), but tragically, “God said to him, ‘You fool! This very night your life will be required of you. Then who will own what you have accumulated” (Luke 12:20)? He had come to possess wealth, not realizing that his wealth had come to possess him. Do we really want any part of this world or the things of the world? Why would we want to go back like the proverbial dog and “return to his vomit” (Prov 26:11; 2 Pet 2:22)? I don’t believe we do if we had enough sense to realize it. Jesus asked, “For what will it profit a man if he gains the whole world and forfeits his soul? Or what shall a man give in return for his soul” (Matt 16:26)? We need help coming out of the world and help getting the world out of us, but God can do all things through Christ (Phil 4:13), and that includes coming out of her you people of His.
Here is some related reading for you: What Does the Bible Say About Babylon: What is its significance? 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible: English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.