Inexpiable

a.	1.
	1.	Admitting of no expiation, atonement, or satisfaction; as, an inexpiable crime or offense.
	2.	Incapable of being mollified or appeased; relentless; implacable. They are at inexpiable war with all establishments. - Burke.

Adj.

1.

inexpiable - incapable of being atoned for

unpardonable