The ONLY way I can see that being a defense is if he wants to claim he killed his kids so they could go to heaven. Other than that, I mean I guess it could go to mental illness?
Doubtful the defence are looking at religion as his prime defence.
It acted a double edged sword for Tim due to his underlying pathology. Initially combined with his capacity for highly literal understanding and rigidity meant once he became committed to those beliefs and found a new sense of purpose it initially reassured , even calmed by the direction he was able to remain unwavering and sustain the general guidance to many reforming behaviours.The religion facilitated improved goal directed behaviours.
The reality it was easiest for Tim to establish and focus on region while in prison where the environment is structured without the magnitude of challenges provided by living in the real world and the multitude of interpersonal relating options or complicated options. Tim's religious adherence did permit his initial success in boosting the strengths remaining in academic technical work areas and being a fiscal provider. These positive outcomes meant he could respond at his peak potential relating to others. That is until inevitably his latent deficits would resurface hightened by general typical stressors.
It is no accident that with Tim's underlying deficits of dramatic brain damage, schizophrenic disease were drawn to selecting the more rigid espoused belief systems contained in highly fundamentalist forms of organised religion. These conditions make those afflicted by their deficits prone to rigid thoughts and responses.
Tim was even viewed by his initial pastor as while extremely sincere as excessively rigid when it came to any form of applying guiding biblical principles posing serious issues in regard to responding to people, enacting appropriate responses. Since he showed that with congregation members it can be taken for granted this would happen in his famial life with wife and children. He would have set precepts of what ought to happen seemingly backed by his extensive memory of biblical phrases he believed supported his literal understanding never mitigated by real life complexity or even children's developmental stages. It would have contributed to familial marital discord.
Furthermore, it would add to experiencing divorce as catastrophic aside from his major concern for children experiencing the loss of having both parents.
Such stressors would escalate Tim's tenuous capacity to contain his deficit prone diseased condition from surfacing more fully. It's not that Tim did not try to the extent he was able to conceptualise as still safe enough to be coping for himself and his children without jeopardising a goal of sole custody in both getting counselling and satisfying the department of children's services, which he did accomplish. Tim, unfortunately was not sufficiently aware as well as understandably inhibited by fear, limited insight of his deficits via damage from injury and schizophrenic disease potential recognise the risks he could pose. Neither the counsellor or children's services were told enough to know either.
Hence, once Tim was becoming symptomatic, his deseased state delusional interpreted his child's curiosity error of behaviour, meant Tim whilst not recognising his exhausted state in coping with kids on his own adding to heightening frustration, did have a psychotic response misinterpreting the child's motivation. Nothing to do with religion here in reasons given. Tim ended up in psychotic fearful rage where he was without any inhibition to remain measured or in control impelled to react so severely he killed the child. Frantic and still psychotic he killed the remaining children. Were Tim in his more rational state he would have played out help seeking calls to 911 focusing on excuses of not meaning it, coached remaining children to shut up. With 5 dead kids you are doomed as a temporary fugitive. Killing all the children Tim had attachments to needed him to have a significant psychotic break of an extreme frenzied self protectiveness disconnecting to all past feelings of caring and protectiveness to his children.
There was no religious ideation present, but voices and notions of child potentially out to get him, some past concepts of other children potential out to get him by colluding with child services, not punishing Amber as he was winning re case for custody and that type of act to punish ex is if at risk of loosing and occurs earlier in separation. Tim had become susceptible to increasing distorted thinking in episodic psychotic thoughts and moments.
While his religiosity confirmed rigid expectations, it restrained him from negative predelictions of substance abuse and illegal reactions.
As a defence, it's how despite his sincere goals Tim could not carry out his ideology by being impacted through the rigidity ensuing of a mind affected by the disease processes of traumatic brain damage , schizophrenic traits signaling impairments disabling goals of church leadership roles despite his sincerity in faith and extensive biblical scripture knowledge in demonstrated applicability.
That's what my guess is in regard to where religion looks to fit and all the defence can do with it in Tim's case.