Regarding the following verse:

“And (remember) the Day He will say: “Call those (so-called) partners of Mine whom you pretended.” Then they will cry unto them, but they will not answer them, and We shall put a barrier between them.”(18:52)

When Allah says “them” who is he referring to? By placing a barrier between the deities that people are worshipping—is Allah referring to the the actual beings, deities, jinn, shayateen people worshipped—or to the idols which have no existence whatsoever? If it is including idols—why would a barrier even be needed if they don’t have an existence?

I read a Sunni tafsir that said the following:

“Allah ta’ala will order the mushrikeen (pagans) to call upon their shurakaa (partners setup in worship with Allah). These partners can be idols, Shaytan or whatever being they associated with Allah in worship. When they call upon these partners, they will not respond to them. The scholars mention for two reasons:
1- If the partners were idols, then there is no reality to their existence.
2- if they worshiped a being, then that being cannot help them.”

I thought this tafsir made sense, so I’m inclined to agree with it, but wanted to get a Shia tafsir of verse 52 of Surah Kahf as well—and if you could answer my earlier question as well. And what websites or books would you recommend for authentic Shia tafsir of the Quran?

The Shia tafsir is that on the Day of Judgment, Allah will address the polytheists by saying to them when they are sentenced to punishment: where are those partners that you ascribed to me? Those idols you worshipped and believed they could help you? Where are they to save you now? God is mocking the pagans through this command. He’s telling them “call on your idols now, let’s see if they can help you.” It’s a rhetorical statement.

As for the “barrier,” that’s not an accurate translation. The Arabic word is موبقا which means place of destruction or perishing or pit of doom. Which basically means that these pagans have no way of seeking help from the idols.

I recommend this Tafsir:

https://www.firstcause.net/quran-english/