This poem is not a faithful description of the Biblical Last Judgment.
Instead of having a bunch of terrible things happen when the angels blow their trumpets, the speaker takes it as a sign for all dead people to wake up and go find their bodies.
In Donne's Christian theology, your soul and body are separated when you die, but you get reunited with your body on Judgment Day.
Donne emphasizes that there are a lot of people who have died throughout history. So many, in fact, that he just lumps them all into some exaggerated, uncountable sum: "numberless infinities."
To make things worse, all these souls have to travel to find their bodies where they died. The bodies are not all in one place – they are "scattered."
Lines 5
All whom the flood did, and fire shall o'erthrow,
The infinite number of dead souls includes all the sinful people in the world, the ones who were destroyed by the Biblical flood that only Noah and his family survived, and the ones who will be consumed in the "fires" that end the world.
The angels aren't just waking some of these bad people, they are waking "All."
So, this line deals only with sinners. The word "o'erthrow" (overthrow) means to defeat or cause the downfall of someone or something.
If you've read the Book of Genesis in the Bible, you'll remember the part about how God drowned the world after deciding that humanity had forgotten about Him and His laws.
Well, not quite everyone. The virtuous Noah was given an advanced warning and allowed to save himself by building an arc.
After the flood, God struck a deal with Noah: no more floods. But sinful people still have to deal with the "fire" after Judgment Day.
Lines 6-7
All whom war, dearth, age, agues, tyrannies,
Despair, law, chance, hath slain, […]
Here the speaker takes another approach to defining "All" souls.
He broadens the category to include every kind of death – all the people who were "slain" or killed by various culprits.
Let's bring out those usual suspects and take 'em one by one: "war" refers to people who died in battle; "dearth" indicates people who died from hunger; "age" makes references to those who died from natural causes; "agues" refers to people who died from sickness; "tyrannies" indicates people who died at the hands of oppressive rulers; "despair" refers to those who killed themselves; "law" means people who were put to death lawfully, and then there's "chance," people who died some accidental death.
This group would seem to include both good and bad people. For example, good people die from sickness just like the bad.
(We encourage you to tuck "ague" into your memory storage attic: it's a cool-sounding word for "sickness." Next time you go to the doctor with a cold, tell her you have an ague.)
There's one last category of people that Donne covers: the people who are still alive but will not be consumed in those end-of-the-world fires. These are the good people who are still living when Judgment Day arrives.
The speaker certainly hopes he will be in this last group.
These lucky few will never have to experience mortality or "taste death's woe." Their "eyes" will look on God in Heaven, as will the good people who had died in the past but have been resurrected.
Now the speaker really has named everyone. Things could have gotten ugly if he had decided to keep naming more groups: "And you whose lips never tasted the foulness of prune juice."
Lines 9
But let them sleep, Lord, and me mourn a space,
Ah, there's a "but" when it comes to the end of the world, isn't there? This is called the "turn" in the sonnet, when the poem shifts topics (see "Form and Meter" for more).
We hear the speaker asking God not to have the angels wake up all these deceased people just yet.
We want to say: but you're the one who ordered him to wake them up! This is like hitting the snooze button on the Apocalypse. Those poor dead people: they are very tired and need their rest. ("Sleep" here is a metaphor for the time between death and resurrection.)
The real reason for this delay comes out in the second half of the line: it's all about "me."
The speaker wants some unspecified period of time to mourn for all the dead people.
Count us skeptical on that one. Do we really think he wants to mourn some long-dead people he has never met?
Lines 10-12
For, if above all these, my sins abound, 'Tis late to ask abundance of thy grace,
When we are there; […]
The speaker worries that his own sins might be greater than those of all the "sleeping" people.
If his sins are really that bad, it will be too late for him to be forgiven on Judgment Day. He needs to start working toward forgiveness now.
His sins "abound" like sand abounds in a desert. "Abound" here means "to have a lot of" or "to be well-stocked with."
It seems like the speaker has a lot of sins, above and beyond the rest of sleeping humanity.
In a lot of older Christian poetry and literature, the way that you show humility is to say that you are the biggest sinner of them all; the worst of the worst. That's what the speaker is doing here.
Judgment Day is described as a place, "there."
The speaker is still talking to God at this point, and he is anticipating the time when he will have to stand before God and account for all his sins.
If he has repented enough, God will show His "grace" through forgiveness. In Christian thinking, God's grace is "abundant" enough that anyone who asks earnestly for forgiveness will be granted it.
