I cannot promise you everything that happens, happens for a reason but can I, without a doubt, promise you that whatever happens, happens wi

I would agree, but would prefer the word 'cause' instead of the last 'reason'.  'Reason' implies some sort of thinking and the temptation of some will be to associate it with 'higher thinking' or some grand plan.

That perspective I'm afraid, is very difficult to subscribe to.

Um, no you can't.

There is randomness throughout the material world, both at the quantum scale and in any suffciently complex system.

You can flap your arms and maybe nothing happens...or maybe it tips the climate system so a typhoon forms off Indonesia that otherwise would have dissipated.

One cannot rationally state random events have discernible causes.

No.