When mystery, Babylon is destroyed, merchants mourn, because the major consumer of the world no longer buys their merchandise:

Revelation 18:11 And the merchants of the earth shall weep and mourn over her; for no man buyeth their merchandise any more:

  12 The merchandise of gold, and silver, and precious stones, and of pearls, and fine linen, and purple, and silk, and scarlet, and all thyine wood, and all manner vessels of ivory, and all manner vessels of most precious wood, and of brass, and iron, and marble,

  13 And cinnamon, and odours, and ointments, and frankincense, and wine, and oil, and fine flour, and wheat, and beasts, and sheep, and horses, and chariots, and slaves, and souls of men.

I understand how all the things in line 12, as well as the first 12 things of line 13, can be bought.

I can even understand, God forbid, how slaves can be bought.

But how had mystery, Babylon been buying souls of men from these same merchants?

I've heard some say this means human trafficking.

However, human trafficking involves selling people for their bodies, for labour or fornication, not selling their souls.

How does one sell souls?

How does one buy souls?