The concrete proof is that the instruction to add Selections is, which is part of the preferred title instructions (6.23.2).  Preferred title for the work is a work attribute.  Expressions do not have preferred titles in RDA.  So in MARC, you add $k Selections after $a Bible just like you would when using "Selections" for a non-religious work with no creator like in this English expression of selections of Arabian nights: $a Arabian nights. $k Selections. $l English.
If you are interested in the historical background on the treatment of "Selections," see 6JSC/LC rep/2 and 6JSC/LC/20 and available here:

Kate James
Policy and Standards Division
Library of Congress

-----Original Message-----
From: Program for Cooperative Cataloging [mailto:[log in to unmask]] On Behalf Of Fiona Grant
Sent: Wednesday, March 23, 2016 9:47 AM
To: [log in to unmask]
Subject: [PCCLIST] RDA Bible Selections

I would appreciate guidance on the following:

Is Selections considered a Work level attribute in RDA and consequently in Bible headings should it come immediately after the $a or $a and $p, by that I mean before any $l, $s or $f?

I've looked at RDA and the NACO participants manual and various presentations/documents and whilst my instinct tells me yes I'm unable to find concrete proof.

With thanks in advance for any guidance,

Fiona Grant
Authority Control and Cataloguing Specialist Collection Development and Description Cambridge University Library West Road Cambridge