As for the reason for the lack of understanding, that's because it doesn't make sense for a real God to do recruiting.
'Unless he has certain intentions…' The demon prince could only assume such, because anything other than the God wanting to use him for some purpose, did not make any sense to him.
"You'll understand once you join me. I can not explain at the moment, because there are some complicated matters as hand, such as my state, and the mortal being that is behind me." God said in order to ease the demon prince's confusion.
"Oh… I get it now. Alright, what do I need to do?" He said, while looking as if he had comprehended everything already. In actuality, he was still in thought…
