that's rubbish.

our existence is the death in my murder analogy. it definitely happened somehow. was it murder, or was the person who died responsible for their own death? if the murderer leaves no evidence that can be linked to anyone, does that automatically mean there was no murderer? of course not. we might have to assume it's a suicide, but it doesn't mean it is.

no evidence does not equal no truth.
and that's where you are stuck. what caused causality? what was the first cause? scientists don't presume to know; that's okay. nothing wrong with that. but it either had to be something outside of causality (whether it's God or a more complex universe with rules that exist outside of causality, or something else) or it goes infinitely into the past.

julz