ISIS recruits would probably be unconcerned as long as their own demise preceded that of their relatives. This is from Olivier Roy's
Jihad and Death: The Appeal of Islamic State.
'Most radicals are deeply immersed in today's 'youth culture'...they go to nightclubs, pick up girls, smoke and drink...[there are] a surprising number of arrests for drink driving, another sign of their low level of religious observance...Their dress habits are those of today's youth: brands, baseball caps, hoods, in other words streetwear...a beard is no longer a sign of devoutness...They never wear the usual Salafi garb - and this is not really to go unnoticed... as they never make a secret of their (re)conversion to Islam.
Their musical tastes are those of the times: they like rap music and go to clubs...[They] are also gaming enthusiasts and are fond of violent American movies such as Brian de Palma's Scarface....kung-fu training rooms and selfies with guns [tend to feature]....There is even a group of jihadi bikers and manga fans in Belgium, the 'Kamikaze Bikers'...some of its members were prosecuted for terrorism....The language spoken by radicals is always that of the country of residence - French, in this case. They often use youth slang and switch to a Salafized version of banlieu talk when they reconvert...Prison time puts them in contact with their radicalized peers....'
This description is important because their final suicidal actions also serve as an act of redemption for their previously wayward lifestyle. More significantly in connection with the proposal you have floated, in the afterlife, according to the eschatological beliefs of ISIS, their status as a
shaheed or martyr confers on them the right to intercede with Allah on behalf of any relatives that subsequently pass on. Often ISIS recruits regard their own relations as possibly destined for Jahannam or hell as they are not following the pure path of salafi-jihadism. Given that ISIS is a doomsday cult, one that is preoccupied with the end times (the appearance of the Mahdi and the antichrist and what not), the fate of their own relatives
in this world rather than the next one may not preoccupy them very much.
I should point out that I only swing by this forum once in a blue moon, usually just to check on what's going on with tinnitus research and only had a look at this section of the forum out of curiosity. So I won't be around to maintain a dialogue.
But if anyone is interested in delving into the murky and sometimes counter-intuitive world of Islamic terrorism, here are the names of a few reputable publications:
William McCants
The ISIS Apocalypse
Graeme Wood
The Way of the Strangers
Peter Neumann
Radicalized : New Jihadists and the Threat to the West
Shiraz Maher
Salafi Jihadism
Jason Burke, Patrick Cockburn and Abdel Bari Atwan are also pretty good.
Maher and Neumann's Twitter feeds are worth keeping tabs on, not just because they feature links to balanced, peer-reviewed research on jihadism but also because there is material on right-wing terror groups as well.
On the relationship of Islamic militancy to early Islam and the Qur'an, Asma Afsaruddin is probably the best author to look at. Here are links to a couple of her articles:
https://renovatio.zaytuna.edu/article/orientalists-militants-and-the-meanings-of-jihadURL]
https://www.juancole.com/2014/07/pretender-islamic-baghdadi.html Finally, with regard to Iran, the late Michael Axworthy's books are seminal. The good news is that - contrary to what unimprovably stupid commentators like Pam Geller would have people believe - the vast majority of Muslim residents in the USA are generally as aspirational and supportive of democracy as any other citizen pursuing the American Dream. In other words, they are generally impervious to the blandishments of the radicals. So here's a reassuring (and quite amusing) video by the taqwacore (Islamic punk) band The Kominas to confirm that: