When Marlow found Kurtz in the centre of the heart of darkness, he had already given in to the powerful forces of darkness. He fell under the spell of the prince of darkness within his own heart. This was no bogey man devil created by religious zealots to scare us into submission. This was the real prince of darkness who resides in us all and who can conquer us as he did Kurtz if we allow it to do that.
Joseph Conrad, through his protagonist Marlow, described Kurtz this way,
“The wilderness has patted him on the head, and behold, it was like a ball—an ivory ball; it had caressed him, and—lo!—he had withered; it had taken him, loved him, embraced him, got into his veins, consumed his flesh, and sealed his soul to its own by the inconceivable ceremonies of some devilish initiation. He was its spoiled and pampered favorite.”
Kurtz had become the pampered favorite of the forces of darkness. As a result, he found unimaginable heaps of ivory. Stacks of it. “You would think there was not a single tusk left either above, or below the ground in the whole country,” Marlow said. That was his ivory. That was what he got in exchange for his soul.
When the Europeans arrived in Africa, as when they arrived in the New World, they were seen as gods. At least some Europeans thought they were seen as gods. Evil gods perhaps, but gods nonetheless. That is what happened after the good intentions of men like Kurtz failed. Many white men succumbed to this dangerous illusion that compared to the indigenous people they were Gods.
This was the original sin! The sin of believing they were superior!
Some whites still suffer from that sin. It continues to stain some of them.