A young man receives a message from "God", and has been told to procreate as fast as possible in order that his descendants can outnumber all the heathens (everyone who isn't his descendants) for a final battle between "good" and evil. Holy fighters must be descendants of the man for them to count, according to "God".

He starts a cult, and within a year has brainwashed 100 young followers (40 male, 60 female) into doing his bidding without question. They've been manipulated using standard cult techniques, and believe this fight is more important than any other cause.

Morality. Legality. Human rights. Their own lives. All mean nothing compared to the will of "god".

How would a cult maximise its population growth? and could this cult become the dominant religion on the planet?

This is near future, so anything plausible is possible, even if its morally repulsive. Cloning is possible but illegal, but they still need a mother to be born from. Infant mortality is basically 0. Life expectancy is 100. Basic robotics but no true AI.

(I did read - Plausibility of this horrible cult, I'm more interested in how to get the horrible cult as large as possible as quickly as possible)

  • 2
    $\begingroup$ Is this just a math problem? You're asking about ideal growth-of-population curve? Or are you asking about a realistic growth-of-population curve? And what constraints are you willing to accept? For example, fast growth often brings unwelcome attention from actors (police, social workers, media) who end cult growth. $\endgroup$
    – user535733
    Commented Sep 17, 2020 at 4:41
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    $\begingroup$ There is a problematic assumption here (besides the subjectivity of "morals"), which is that descendents of the cult founder will be members of the cult. $\endgroup$
    – jamesqf
    Commented Sep 17, 2020 at 5:27
  • $\begingroup$ I understand that Excel costs money, but Google Sheets and LibreOffice Calc are free to use. $\endgroup$
    – AlexP
    Commented Sep 17, 2020 at 7:06
  • 2
    $\begingroup$ Sounds like a perfectly normal game of Crusader Kings to me… $\endgroup$ Commented Sep 17, 2020 at 20:31
  • 1
    $\begingroup$ So...you are planning to create more progeny of our lord and saviour Elon Musk? $\endgroup$
    – Herman
    Commented Sep 18, 2020 at 8:38

4 Answers 4


Assuming you're not raided by the cops, 80 years to the dominant religion.

Assuming your cult is comfortable breaking these taboos:

  • Hebephilia
  • Cloning of embryos (splitting them)
  • Asexual reproduction
  • Basically every human right

You could overtake Catholicism as the dominant religion within 80 years.

Simulation in C++. This is based on an answer I gave to the similar question: Population Size of a Colony With a Large Gender Disparity

Typically in these cults the female members are used as a harem of the founder. This isn't fast enough, and its dependant on ovulation cycles, and may produce more men than needed. If the founder truly believes this is a divine mission, he'll abstain from sex with his flock. A good litmus test of actual belief or greed of founder IMHO.

So all 60 women need to have eggs harvested immediately, the founder needs his sperm extracted immediately, 60 female embryos are created. Each embryo is split into at least 3, 2 are implanted, the remainder is stored.

I'm assuming with future medical tech, that IVF has a 100% success rate. If this isn't true, just split the embryo into more pieces and implant how ever many are needed to get guaranteed twins.

IVF is tricky, but can be automated with the advanced robotics your cult somehow has access to.

With current medical tech, premature twins at 22 weeks can survive, but that does seem like the exception rather than the rule, even with future tech. I'm going to assume your medicine is advanced enough to give birth at 30 weeks, the infants are then treated using robotics and advanced premature baby meds.

This gives a cycle of 3 sets of identical twins every 2 years (average of 3 per year). Your first generation mothers must truly believe in the cause, because them and their children will not have a good life.

1 in 100 children is put aside for income, the rest are going to be used for more breeding.

Average age of puberty in females currently is 11, and even though there are cases of 5 year old mothers, that's not going to be reliable enough for this kind of population growth. I'm going to assume that your advanced medicine gives you access to growth hormones to speed up maturity so that the body of an adult is formed sufficiently well that IVF reproduction is reliable 12 years after birth.

Those first 12 years are basically spent with the children memorising theology and how they're going straight to heaven if they're used as baby factories. The less they learn, the better. Once they hit 12, they're implanted with 2 * cloned embryos of themselves, either from storage, or they could be self-cloned (essentially asexual reproduction).

The starting males are basically used to earn resources to buy food, power, robots, and land for the expanding cult. 40 people earning decent wages but living very frugally (zero personal expenses frugally) can earn lots of money for the cult.

The 1 female child in 100 should be further educated, in addition to theology, she should be taught basic reading and writing etc. She should be sent to work in a supermarket / fast food joint as soon as they'll hire her (say, 15), and then when she turns 18, sent to work in a field which an untrained young female earns a tonne of money, (stripping or sex work). After her income starts to decay, she joins the breeding pool.

I don't believe you'll get compliance from the women with this massive baby farm operation, they'll revolt. Assuming the revolt is suppressed, this could end up with a hentai-like factory with thousands of women bolted to frames with tubes coming out of them - you said zero morals.

Once the women hit menopause (average age 51), rather than extend it with drugs, and assuming they're still loyal and not bolted to some breeding frame against their will, I think they should be sent out into the workforce to earn money for the cult.

After 78 years of this, you'll have 670 million children born that year, and get a total population of about 3.4 billion.

First 12 years you'll have 180 female children born each year on average. Then

  • Year 13 : 720 births
  • Year 14 : 1260 births
  • Year 20 : 4500
  • Year 30 : 34200
  • Year 40 : 228,960
  • Year 50 : 2,312,280
  • Year 60 : 18,070,020
  • Year 70 : 148,197,600

C++ source code:

#include <vector>
#include <set>
#include <iostream>
#include <algorithm>

int main()
    std::vector<size_t> males(20,0);
    std::vector<size_t> females(20,0);


    for (auto year = 0; year < 78; year++)
        // Calculate our births
        size_t newMales = 0;
        size_t newFemales = 0;

        // Women of these ages will be used for children
        for (auto age = 12; age < 51; age++)
            if (females.size() <= age) break;
            //newMales += females[age] / 2;
            newFemales += females[age] * 3;

        males.insert(males.begin(), newMales);
        females.insert(females.begin(), newFemales);

        // Print some stats

        std::cout << 
            "Y: " << year << ". " 
            << newMales << "m and " 
            << newFemales << "f born.\n";

    std::cout << "At end of simulation: \n";

    size_t total = 0;
    size_t infants = 0;
    size_t children = 0;
    size_t teenages = 0;
    size_t youngAdults = 0;
    size_t adults = 0;
    size_t seniors = 0;
    size_t male = 0;
    size_t female = 0;
    for (auto age = 0; age < 100; age++)
        if (age >= females.size()) continue;
        std::cout << age << " yr olds: " << males[age] << " males and " << females[age] << " females.\n";
        auto t = males[age] + females[age];
        male += males[age];
        female += females[age];

        if (age < 5) infants += t;
        else if (age < 13) children += t;
        else if (age < 20) teenages += t;
        else if (age < 35) youngAdults += t;
        else if (age < 51) adults += t;
        else seniors += t;

        total += t;

    std::cout << "Total " << total << "\n";
    std::cout << "Infants " << infants << "\n";
    std::cout << "Children " << children << "\n";
    std::cout << "Teens " << teenages << "\n";
    std::cout << "YoungAdults " << youngAdults << "\n";
    std::cout << "Adults " << adults << "\n";
    std::cout << "Seniors " << seniors << "\n";

    std::cout << "Males " << male << "\n";
    std::cout << "Females " << female << "\n";
    return 0;
  • 9
    $\begingroup$ If it's not important that they be cult members, only that they descend from the leader, send the male offspring out into the world with 18 years training in picking up women. They can then continue spreading the holy seed in the outside world while the internal effort continues. $\endgroup$ Commented Sep 17, 2020 at 14:46
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    $\begingroup$ @CristobolPolychronopolis If it's not important that they be cult members, have all males donate to sperm banks as frequently as possible. $\endgroup$
    – Ryan_L
    Commented Sep 17, 2020 at 23:24

You can take a page out of these monsters book: https://www.nytimes.com/2019/08/21/health/sperm-donors-fraud-doctors.html

These doctors at fertility clinics used their own sperm instead of the selected donor sperm. For example:

According to the Dutch Donor Child Foundation, DNA testing has confirmed that a fertility specialist, Dr. Jan Karbaat, fathered 56 children, born to women who visited his clinic outside Rotterdam. Dutch authorities closed his practice in 2009, and he died in April 2017 at age 89.

Your cultists could all get jobs at fertility clinics distributing their prophet's sperm en masse. Since it is set in the future you could have one cultist be a biologist who is capable of mass producing sperm from smaller samples in a lab they work at or using equipment they acquire/steal. Then the sky is the limit.

  • 2
    $\begingroup$ This is a good idea in that the cult doesn't need members descended from the initial 60 female followers, it just needs members descended from the leader; on the other hand, it requires tracking every child born from this activity and indoctrinating them into the cult. $\endgroup$ Commented Sep 17, 2020 at 18:07
  • 1
    $\begingroup$ @RossPresser good point. The cult could keep files on all recipients. Then later they use these to track down the descendents when they come of age, forcing them to join the cult or killing them. You can even have a protagonist detective who is investigating the string of murders and uncovers the whole thing. $\endgroup$
    – onb
    Commented Sep 18, 2020 at 19:07

Life expectancy is high and mortality low. You need to have people procreating as much as possible (I am not covering how you are going to get resources to feed all the cult members).

The cult can set a religious festival which main purpose is to have as many as possible women pregnant. This could be a 2 weeks festival during which it is considered good deed from every sexually mature cultist to offer at least one daily unprotected intercourse to the greater good of the god.

This would have the side effect of synchronizing most of the births in a relatively short period of time, making it easier to have a collective effort in taking care of the newborn

  • $\begingroup$ and with future technology to confirmed father of the child mother and father will received insert god unit here which accumulated for every child they conceived and get promote in cult as certain rank or using it to trade for privilege (or gift voucher) $\endgroup$ Commented Sep 17, 2020 at 4:03

Assuming he has children with all available members of his cult at the start, the entire world being descended from him is almost inevidable in time. The bigger problem is conversion and keeping his desendants beliefs. Since you can only be a true member by birth, his cult will have trouble attracting new members, and eventually, even having the beliefs passed on when only one parent follows the religion. If modified so that the parent of a descendant is also saved his religion is far more likely to spread.


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