It’s explained that the Xenomorph is the galaxy’s perfect killing machine.
This is a notion that hangs over the rest of the Alien series.
Since Aliens, at the end of the day, functions as an action spectacular more than anything (the oft-discussed theories of motherhood notwithstanding), its religious symbolism is difficult to see.
And, in the most obvious religious allusion, the film’s protagonist, Ellen Ripley, sacrifices herself to save herself and others (she throws herself into a pit of molten metal when she learns a new creature will be borne of her abdomen).
He is, perhaps, arguing that humanity has run afoul of God and broken the old Covenant–perhaps by crucifying Christ–and that a Satanic force has been released to take us out.