There was a kind of fall of the angels. Their soul, misled by malignant spirits, trusting the promises of Lucifer, decided to separate from their creator. They fell in the visible world, i.e. on the ground. They entered the bodies created by the devil. From then on, they were prisoners of their carnal gangue, they could not however forget their celestial origin.
The divine spark persisted in them, in spite of
their treason betrayal, of the sins of which they took care in their
new state. They remained immortal.
When they're died, they were reincarnated in another body and that indefinitely.
Seized of pity, God had sent his son Jesus-Christ. Here the cathares separated definitely from the Catholics. For the latter, Jesus had incarnated and sacrificed for the safety of men. The teaching and the rites of the Catholic Church were based on the sacrifice redeemer of Jesus.
Cathares read the writings differently: for them Christ had come to deliver a message and to offer men the key of their safety.
Of divine nature it had not been incarnated but only taken the human appearance. Christ would not have allowed that it underwent the dreadful Crucifixion. The torturer of the Golgotha had crucified only a shadow.
Therefore there had not been redemption, but a call. Jesus had come to draw the fallen souls from their sleep, to suggest them a model of life. He had poked the divine sparks hidden in their body.
The end of the world was not catastrophic, but a progressive extinction; the saved souls left the ground, Satan was staying alone in its nothing, marking the separation of the two principles.