The distinction between appearance and reality is an old saw in philosophy. It appears in the letters to the churches (Revelation 2-3) as an opposition between being and saying, a (distinctively Hebraic?) emphasis on the word.

Several letters describe the challenge. At Ephesus, there are “saying apostles” who are not apostles. The angel at Smyrna has to deal with “saying Jews” who are not true Jews, and at Thyatira there is a woman Jezebel who is a “saying prophetess.” 

The Ephesian angel is commended for “testing” the false apostles and “finding out” their falsehood. It is not so much a matter of penetrating a veil to a reality behind it (penetrating past the seeming to the being); it is more a matter of testing to discover that the saying is a false saying. The assumption is that everyone is a “saying something,” but some speak falsehoods.

On the other hand, the angel at Thyatira doesn’t deal with Jezebel as he ought. It’s not clear whether or not he believes her saying. But skepticism is not enough. Jesus expects him to be intolerant (2:20).

Testing what others say about themselves is essential to the work of an angel, because the angel of the church oversees the teaching that happens in the church. The angel at Pergamum is the one who is charged with “having” (exeis, singular, 2:14) Balaamites, and the angel at Thyatira is the one who is faulted for “tolerating” (apheis, singular, 2:20) Jezebel. Teaching is regulated by the angels of the churches.