Not Chaos Energy.

His consciousness felt the feeling of a fall for a long time. His mind descended past the abyss into an unfamiliar place with thick, corrosive energy. He is familiar with this type of energy because it is the one that comes out of his mark of sin. He has gained immunity to this type of energy, so he wasn't harmed. 

"It seems I was wrong about my conjecture. But where does this Chaos energy come from? Is there a large mark of sin somewhere here?"

He didn't feel danger, so he remained calm and interested in this strange place that he didn't know existed until now. He examined it as his consciousness sank deeper into the Chaos energy. 

But then his consciousness started to become pressured by the energy around him. It is the same pressure that his soul experienced from Chaos energy when he was a fledgling. The difference is that what is surrounding him isn't Chaos energy anymore. 

"What is this?" He exclaimed in panic. "It is so corrosive."