https://www.quora.com/What-does-selling-your-soul-mean/answer/Desmond-Last
It means that you walk with Evil as if Evil were part of your life. Your apathy becomes the New Evil as Evil is unable to exist without you and your selfish greed and hypocrisy.
Should you be a Prime Minister then your apathy to the pain of all those your deeds of selling weapons of war will join you with Evil. Each child you kill when you sell your weapons of destruction to those who tear apart the screaming bloodied bodies of the children of war is a ledger to Hell.
Your soul will be sent to Hell for an eternity for God knows that you did not stand for Good but you laid down for Evil to run its searing rake of corrupted religion over the stinking mire of false human rights you proclaim to the World.
Each night God sends you those bloodied bodies with limbs torn asunder screaming so loud you can never sleep.
You see the pit of Hell’s Furnace each night getting closer and closer to you. Its flames searing your body as you awake in a sweat of fear.
Evil has no friend as you too have no friends. You can only buy your companions of soulless delight who sycophant to your rank or wealth only to one day spit on your grave.
That is what selling your soul does it removes those children of bloodied limbs and screaming pain and instead replaces it with the sterile of collateral damage – your apathy now a new name. But not hiding your soul now twinned with Evil.
Your soul is now sold. You have been bought and paid for. You have no place with God and must one day pay the price – an Eternity of screaming, frenzied pain; each nerve on fire each bone aflame. Your soul now an ember of Hells Inferno.