The book of Revelation reveals that one day, angels are going to harvest the grapes of the Earth and gather them into the great winepress of God’s wrath. Then someone (identified later in the book as Jesus) is going to trample those grapes until he’s surrounded by an enormous flood of blood from the grapes.

So that’s kinda weird. Why would grapes have blood in them? Is this supposed to be some kind of miracle or something? I don’t normally do this, but let’s assume the Bible is making a metaphor, and see where that takes us. Maybe when it says blood, it means grape juice!

…Or maybe when it says grapes, it means people. Yeah, that one’s more interesting. And more likely to be what they intended, I guess. So, how many people would Jesus have to murder to get that much blood? Let’s find out…

Just how much blood is this?

The Bible says there will be so much blood that it will be as high as a horse’s bridle for 1600 stadia.

The height of a horse’s bridle is inconveniently variable, since horses can move their heads up and down quite a bit. But I think the bridle would normally be around the same height as the shoulder blades, which is where the height of a horse is measured. And the average horse is a bit over five feet tall.

How long is 1600 stadia? That’s hard to say as well, since ancient Greek units of measurement weren’t standardized very well. But a stadion is probably at least 500 feet, so 1600 of them would be at least 800,000 feet.

So is that 800,000 feet out in all directions, or just from end to end? What shape is this pool of blood? The Bible doesn’t provide a lot of details, so let’s just keep it simple and estimate that it’s in the shape of something like a 5-foot-tall cylinder with an 800,000-foot diameter. So that’s about 2.5 trillion cubic feet of blood.

The average adult only contains about 5 liters of blood, so you’d need to kill well over 10 trillion people to get that much blood. In reality, that’s probably more humans than will ever live. But if it wasn’t, how long would it take before we would have that many humans, so Jesus could stomp them all to death?

What’s the quickest time we could take to get there?

Let’s assume that starting now, every female human is going to repeatedly get pregnant nonstop from age 5 to age 73, and each pregnancy is only going to last 21 weeks, and they’re going to have nonuplets every time, and no one is going to die until we get to the winepress incident.

And let’s say all the new kids being born are going to be girls (since the maximum possible overall birth frequency is proportional to the number of females, and isn’t really affected by the number of males).

Under these assumptions, each woman would have about 1500 daughters in her lifetime. So basically each generation is going to have 1500 times as many women as the previous one. If we start with billions of women, we’d be in the quadrillions in just a couple of generations. So the lower bound for how long it could take is not very long.

Let’s make this more realistic

Currently the average woman only gives birth to a bit more than two children in her lifetime, not 1500, and even that number is declining. That’s barely enough to keep up with the rate people are dying. So at current rates, the world population probably isn’t going to change all that much.

We’ll never get to 10 trillion at this rate. And I don’t think a shorter generation time would make any difference under these conditions. The most realistic way to make this happen would be to increase the birth rate.

Suppose everybody stops using contraception for some reason. Out of the 2 billion or so women of reproductive age in the world, about half of them are sexually active and capable of reproducing but don’t currently want to. And about half of women of reproductive age are using some kind of contraceptive method. I’ll assume those are pretty much the same billion women. So if everybody stopped using contraception, there would be twice as many women having children.

So does that mean the average number of children a woman has would double? When Romania banned contraception (among other things), they got their average number of children per woman up close to four. And there are countries that have even higher fertility rates, even without legally enforcing it.

So let’s say the worldwide lifetime average number of children per woman goes up to four, so each generation is twice the size of the previous one. In ten generations, there would be close to 10 trillion people just in the latest generation. And there would still be people alive from previous generations to make up the rest. The average generation time is about 25 years, so that would take around 250 years.

Except contraception apparently doesn’t really affect fertility rates in the long term (since most people aren’t trying to never have kids). So Jesus’s squash-ten-trillion-people-to-death-in-a-winepress plan might not be possible even if everyone stops using contraception, which isn’t going to happen anyway.

What if instead of increasing the birth rate, we managed to figure out how to mostly stop people from dying? With the average woman having about two children, each generation would be about the same size as the previous one, but in this scenario all generations from now on will continue to exist indefinitely. The population would increase by 8 billion every generation. So dividing the target population level by the current one, it would take about 1250 generations to get to 10 trillion people, or over 30,000 years.

But in reality…

The world population is expected to peak this century, so realistically, it doesn’t seem likely we’ll ever get to 10 trillion. Let’s not forget that the total fertility rate is actually declining, and as a result, the world population will probably also start declining before long.

Can the Earth’s resources even sustainably support trillions of people at a time? Some people think we’re already at or beyond the Earth’s maximum carrying capacity with just 8 billion people. If there ever are 10 trillion people alive, by then we probably won’t all be living on Earth. But Jesus’s plans only include trampling people harvested from Earth.

Sorry Jesus, you’re never going to get that much blood. Unless you intend to do a loaves-and-fishes kind of thing and get all that blood from just a few victims. Or unless the Bible really did mean to say there are going to be bleeding grapes in that winepress.