The Maggid of Beit Yosef

Good evening!
The Beit Yosef writes that an angel appeared to him several times and revealed the secrets of the Torah to him, and he writes the simpler parts in the book. Rabbi Elkabetz (or Rabbi Najera) also writes that on Shavuot night they saw with their own eyes that the Beit Yosef said words of Torah that seemed to be spoken by someone else, and the Rabbi himself confirmed this.
This is seemingly overwhelming evidence of the existence of the matter, isn't it?
It seems to me that there is not a single person who would say that Beit Yosef is a liar (since even if one can lie for the sake of high value…, this is not the case of course). And likewise, it is not right to say that he is delusional, because this is someone who wrote the most refined Shulchan, and likewise, the rabbis around him testified to this, and likewise, he revealed some of those secrets.
And yet I would love to hear how an honest and sincere atheist would deal with this?
Thank you very much!