Adrian knew what the God of Death was telling him and that was to not involve himself with other religions as him being a champion is equivalent to being a herald of the twin gods. His actions could be seen as a challenge in the face of the other gods if he were to involve himself with their practices. Although when Abaddon said that he also interpreted it as if you want to be free from the oppression of other gods in the mortal plane then become much stronger than them so that Adrian's very presence itself would become a deterrent.
Adrian bowed towards the two gods as he has already took too much time just by staying here in the Nether realm and he was already given the mission.
