The voice from above is the higher mind calling the awareness out of Babylon, which is the confused outer self built on trade, appetite, and borrowed opinion. To come out of her is to withdraw attention from that whole apparatus of gain and craving before it drags the finer part of a person down into its own diseases. The plagues are what the outer self inevitably suffers, and the warning is that identifying with it means sharing its fate. What is being separated here is not a body from a city but the still center of consciousness from the noisy market it has mistaken for home. When attention lifts to the crown, the fever of that lower life no longer reaches it.
Babylon: the crowded outer self of trade, appetite, and confusion, raised on borrowed thought
Heaven: the crown of the head, the high seat of consciousness from which the true voice speaks