"When the end is uncertain, something you are not sure of, and you've still got hope, it is the sheer culmination of a purest wish and hope for life, left to the hands of destiny."
Now that the spacing problem is fixed, reading the sentence brings out other problems. The commas aren't the main problem. I'd start by trying to identify what the "it" underlined refers to. The problem is that it's not possible to say where the commas should go if the sentence is not understandable.
As I read it, the end is uncertain, but you still have hope. Something, then, is the culmination of a wish for life. And I think that either 'life' or that 'something' is left to the hands of destiny. If you could clarify those points, we could fix the commas.