In my experience, the biggest issue ‘spiritual’ people have with life is a fundamental misunderstanding about individuality.
I once had a discussion with someone who said that the parents of a disabled child were right to have an abortion, and that their child would thank them when ‘they’ were born able-bodied. This makes the fundamental mistake of believing that something (a soul or whatever) is waiting in the wings, marked ‘child 1’, just waiting for the first child to pop out of the womb, if the disabled child was born, child 1’s soul would become the disabled child, if not, the next child would get the same soul, would be the same ‘they’, and would be happy to have been born with the able body instead of the disabled body.
This is often a view that goes hand-in-hand with reincarnation and the belief in pre-existent souls, which God ‘sends’ rather than ‘creates’ at the moment of birth/conception.
The problem with this is it means ‘my’ soul isn’t really mine, it’s just a parasite that’s living temporarily in my body. ‘I’ (the physical me, with memories, emotions, desires, etc.) have to do good works in this life in order to benefit the welfare of my ‘soul’ which then goes on somewhere else, where it will not share my memories, body, emotions, or desires, in other words, where it will leave anything constitutive of ‘me’ behind. This is in some ways similar to Buddhism, but not authentic Buddhism, rather the cod-spirituality version that is sold in the West (as a friend once put it, the third school of Buddhism, Mahayana, Theravada and Califirniyana

)
The fundamental point, whether you believe in a ‘soul’ or not, is that each child is unique. Genetically, each child born to the same couple will combine the couple’s DNA differently, and will be influenced by innumerable factors in the womb. Nobody (even an identical twin) is the same ‘person’ as their brothers and sisters, this is obvious. If one child dies in the womb, the next child will not be the same, nor a replacement. It may be comforting at first for the mother to believe that this is the same child come back, but at the end of the day it is profoundly damaging to the child’s sense of self-esteem and individuality (read Roddy Doyle’s
A Star Called Henry and you’ll see the damage such lack of individuality can do!) It’s precisely our uniqueness that gives us value as human persons, and that we should, as ‘spiritual’ people, give thanks for.