Letter of condolence - finding the words

[PlumpAndDeliciousFatcat]

I'm writing a letter of condolence to a bereaved parent. Their adult child has died young and although I write for a living I am struggling to find the words. Reading MN threads has helped me before to know what to say (and more importantly, what not to say) in some difficult situations so I'd be so grateful if anyone could share what helps, and what doesn't.

The deceased was a young adult and they died after a short illness.

From experience, whatever you write will feel not quite right, so you agonise and agonise about it, but as long as it’s heartfelt, IMO it’ll be taken in the spirit intended.

I recently had to find the words for a couple whose baby had died at just a few months old. That was the worst I’ve ever had to agonise over.

It really doesn’t matter much what you actually write, OP. It’s the fact that you bothered to, and that you care - that is what they will take from it.
Perhaps just state the obvious - that there are no words that can take away their grief, but you want them to know you are thinking of them.
You could add a nice reminiscence about the deceased, something you admired them for, or something funny they did as a child. Something that celebrates their life, not just grieves their death.
I often quote the memorial at the Water of Leith in Edinburgh: “Grief is not forever. But love is.”
Finally, if you, and/or they, have a religious faith, you could add that you are praying for them, and ask God to support them in their loss and reunite them with their loved one at their life’s end.

Thank you all. I really appreciate your thoughts.

Finally, if you, and/or they, have a religious faith, you could add that you are praying for them, and ask God to support them in their loss and reunite them with their loved one at their life’s end.

I think this is part of the reason for my writer's block. I am religious but the bereaved person is very much not, and from prior experience I know that they would respond angrily to any mention of faith or even general spirituality. I would never ever force my faith on someone else, especially in this situation, but I am hyper-aware of not giving this impression.

I am a Christian, OP, and I agree it’s difficult when the bereaved person is an atheist. It’s much harder to comfort someone who believes their loss is permanent, and that life and death are meaningless and unfair.
However, that is their choice and you have to respect it. All you can do is write a neutral letter, but pray to God on their behalf.