Relatedly, Khan Güyük likely already understood the basic tenets of Christianity as Christianity had existed among the Mongols as a substantial minority religion for at least one or two centuries at that point. I think Khan Güyük actually had Christian relatives, though he himself was shamanist. It was even the Mongols who reintroduced Christianity to China, after it had been earlier wiped out.

Europeans were completely oblivious to all of this, however.