To start off my reference: Carrasco, David. The Aztecs: A Very Short Introduction. Oxford University Press, 2012. EBSCOhost, search.ebscohost.com/login.aspx?direct=true&db=e000xna&AN=405897&site=eds-live&scope=site.

Can’t recommend him enough if you are interested in learning more about Aztecs and their mythology.

First I’ll answer your second question. Why does Aztec mythology seem so hard-core? Well, the first accounts we have of Aztec rituals and mythology comes from firsthand accounts of some conquistadores, for example Bernal Diaz del Castillo. There are some accounts that said that as many as 80,000 enemy warriors were sacrificed in a 4 day ceremony, but excavations in the Great Temple of Tenochtitlan only uncovered 126 people buried in over 30 seasons of research. This is because Spanish chroniclers exaggerated the numbers and purposes of these sacrifices as a strategy to justify their own conquest and violence during the conquest. So from this chronicles we know that there were exaggerations with both rituals and mythology.

Now unto your first question. Life for Aztecs was not a living hell, sure war was a common thing, it was essential for their empire. They had special wars called Xochiyaoyotl (flower wars) whose main objective was to capture people to be sacrificed to the gods and death in the battlefield was called xochimiquiztli (flowery death). And with war they managed to subdue different tribes who had to pay them tributes; if you lived in the Aztec triple alliance you were pretty well off.

Regarding their mythology, I will need to explain a bit about how they viewed death and blood and how it relates to their cosmovision so please bear with me. For the Aztecs there were two space-time places that were connected, one where the gods lived and the other one with the rest of us. When the Gods created this second space-time inhibited by us some of them violated divine laws and were expelled, in the darkness they created the first fire and Nanahuatzin jumped into it becoming the sun and giving his divine substance to the world, the rest of the Gods followed suit and everything and everyone else was created. Because of this everything in this world has some divine substance. So when a human or animal dies the divine substance is released and it returns to the underworld where it waits its rebirth. Now these Gods need nourishment, refreshment, payback, and renewal. Only human blood was sufficient to nourish the Gods and Aztecs realized that they owed the Gods for the creation of the world. They didn’t have a word for sacrifice, instead they used the word nextlahualtin which means payment or restitutions. So in their eyes they were returning the divine essence that the Gods first used to create the world. And get this, the most common form of sacrifice was autosacrifice that was done with the use of maguey thorns to pierce one’s earlobes, thighs, arms, tongue or genitals. 

The life of the average Aztec was far from hell on earth. In fact, it could be argued that the Aztecs had some of the highest living standards in the world at the time, depending on how you define them. Of course, details varied throughout Central Mexico, but in general they were well fed, had strong local governments, thriving trade networks, and an effective legal system.

The portrayal of Aztec Mythology as especially ‘hardcore’ as you say owes more to the Spaniards than any realistic interpretation of their worldview. Remember, the Spanish considered any religion to be demonic if it was not Christian (and later, not Catholic), and so their depiction of Aztec religion was tainted by this assumption. The problem has been exacerbated by the portrayal of Aztec beliefs in popular culture where they appear without explanation or context, making it look as though the Aztecs killed people for the sake of it, or that the gods literally ate people. Neither is really accurate.

Furthermore, the Aztecs were not really trying to avert the apocalypse. Although disaster could result in famines and droughts, the actual apocalypse wasn’t really relevant for them. The idea that the end of the world was imminent comes from Christianity. Millennialism was on the rise among priests in the early 16th century, and this coloured their views on Mesoamerican religion. Themes of torment and torture were used by the friars to ‘encourage’ conversion, thus introducing apocalyptic ideas to Mesoamerican civilisations. The belief was then revived by the New Age movement when the Classic Maya civilisation was uncovered, and their calendrical system badly misinterpreted.

So, what is really happening here? In order to explain it, I’m going to give you a brief description of the Legend of the Suns as found in the Florentine Codex (I know this has already been mentioned in the thread, but it is important to ensure that it is understood correctly). According to Aztec mythology there were five suns. Each sun was ruled by a different god. The first was Tezcatlipoca. However, he was a shadow god, and so couldn’t shine brightly enough. So, Quetzalcoatl knocked him down and took over. Not happy with this, Tezcatlipoca turns into a jaguar and devours the sun. After this Tlaloc, the rain god takes over. His reign is brought to an end when Tezcatlipoca stole his wife, Xochiquetzal. In anger, he makes it rain fire. After this his sister, Chalchiutlicue, takes over as the sun. This sun ends with a massive flood. This sets the scene for the 5th sun, which is the important part.

To create the 5th sun, the gods gathered at Teotihuacan. Two gods, Nanahuatzin and Tecuciztecatl, volunteered to jump into a big bonfire and become the sun. However, Tecuciztecatl was too cowardly to enter, so Nanahuatzin did instead. He subsequently emerged as the new sun god Tonatiuh. But there was a problem. The new sun could not move. And so, the other gods agreed that they should be sacrificed, and the power of their deaths used to send the sun on its course. Now, although the myth does involve a heavy amount of sacrifice it is important to note how the Aztecs interpreted it. First, destruction leads to creation. There is no real end, and everything that is old is made new again through cosmic cycles. Second, the cosmos was created and ordered with an act of blood sacrifice conducted by the gods on behalf of humanity (well, life on earth). We see Nanahuatzin ‘die’ and then be reborn as Tonatiuh. Aztec religious practices and beliefs mostly stem from these principles.

We must note now that the Aztecs had no word for sacrifice. The word they used was nextlahualli, which translates to ‘debt payment.’ Debt payment does not refer exclusively to blood sacrifices though, it covers all forms of offerings including flowers, incense, jewels, dances, prayers, poetry, and manufactured goods. The reason people think of the Aztec gods as bloodthirsty is that they take human sacrifice outside of the entire offering complex of Aztec theology. Human victims were the most extreme form of offering, but they were far from the most common type. Blood was included, because blood was life, and so people were giving life back to the gods, as the gods had originally given blood to them. Another part of the Legend of the Suns covers this. Quetzalcoatl travelled to the underworld to recover the bones of humanity. He succeeds, and takes the remains to the Cihuacoatl. She kneads the bones, and Quetzalcoatl drains blood from his penis and adds it to the mixture. Regardless, the point is that Aztecs sacrificed to show gratitude and respect. They believed they had a debt to the gods and a responsibility to worship them.

Rituals were multi-faceted events intended to accomplish several goals. One was described by David Carrasco as ‘world renewing.’ This goes back to the rebirth of the sun. As the gods were locked into a cycle of death and rebirth, the Aztecs used rituals to regenerate, restore, and reorder, the world, both naturally and cosmically. To do this, ceremonies repeated the events of the original myths. The central figure was known as an Ixiptla, or god impersonator. This was usually a person, but could have also been an idol or effigy. The ixiptla helped to re-enact the myth, thereby restoring the earth to a more ordered (and more fertile) state. This belief system actually gives people some agency. Humans had to take a leading role in maintaining the health and stability of the world and human action was important. It is also worth pointing out that ceremonies were larger when resources were plentiful, probably due to the need to pay their ‘debts.’

To summaries, Aztec religion was based on fertility, regeneration, and reciprocity. Ceremonial practices were based around paying debts to the gods and restoring balance to the world. Aztec religion is not especially hardcore when compared to other mythologies (including Christian myths). It just happens to include a few things that Europeans are especially shocked by (i.e. blood), and therefore obsess about while ignoring everything around it. I’ve waffled on enough. I’ll let an Aztec have the last word. Motecuhzoma himself reportedly told Cortés that, ‘We hold them [the gods] to be very good. They give us health and rain and crops and weather, and all the victories we desire.’

Sources: Benson, Elizabeth and Boone, Elizabeth H.: Ritual Human Sacrifice in Mesoamerica, (Washington D.C.: Dumbarton Oaks, 1984)

Sahagún, Bernardino de: General History of the things of New Spain Book 7: The Sun, Moon, and Stars, and the Binding of Years, tr. by Arthur O.J. Anderson, and Charles E. Dibble, (Santa Fe: University of Utah, 1979)

Carrasco, Davíd: Religions of Mesoamerica: Cosmovision and Ceremonial Centers, (Long Grove: Waveland Press, 1990)

Kerkhove, Ray: ‘Dark Religion? Aztec Perspectives on Human Sacrifice’, Sydney Studies in Religion (2008)

Luján, Leonardo López: The Offerings of the Templo Mayor of Tenochtitlan, tr. Bernard R. Ortiz de Montellano and Themla Ortiz de Montellano, (Niwot: University Press of Colorado, 1994)

Miller, Mary and Taube, Karl: An Illustrated Dictionary of the Gods and Symbols of Ancient Mexico and the Maya, (London: Thames and Hudson, 1993)

Montellano, Bernard R. Ortiz de: Aztec Medicine, Health, and Nutrition, (New Brunswick and London: Rutgers University Press, 1990)

Nagao, Debra: Mexica Buried Offerings: A Historical and Contextual Analysis, (Oxford: BAR International Series 235, 1985)

Pennock, Caroline Dodds: ‘Mass Murder or Religious Homicide? Rethinking Human Sacrifice and Interpersonal Violence in Aztec Society’, Historical Social Research/Historische Sozalforschung, 37:3, (2012)

Restall, Matthew and Solari, Amara: 2012 and the End of the World: The Western Roots of the Maya Apocalypse, (Plymouth: Rowan and Littlefield Publishers, 2011)

Sandstrom, Alan R.: Corn is Our Blood: Culture and Ethnic Identity in a Contemporary Aztec Indian Village, (Norman: University of Oklahoma Press, 1991)

Sigal, Pete: The Flower and the Scorpion: Sexuality and Ritual in Early Nahua Culture, (Durham: Duke University Press, 2011)

Smith. Michael E.: At Home with the Aztecs: An archaeologist uncovers their daily life, (London and New York: Routledge, 2016)

Ross Hassig, in his book Aztec Warfare, talks about how the Aztec Empire was structured. A key factor, in Hassig's view, was the limitation of Aztec transport technology. The Aztecs had no wheeled vehicles and no draft animals. They did sometimes use canoe-like boats, but overland all goods had to be transported by human bearers.

Politically, this led to an empire structured somewhat differently than empires elsewhere. The pattern of looting conquered provinces and sending the proceeds back to the capital didn't work too well, stuff was difficult to transport. Instead what the Aztecs did was set up a system of tribute where conquered cities were required to provide supplies on demand to support the Aztec armies. Much of this support was in the form of food, as well as commitments to provide bearers to carry the supplies. The supplies would be stockpiled in the tributary city, and picked up by Aztec armies en route to battle.

What does this have to do with religion? Well, the Aztecs avoided stationing garrison troops in tributary cities, preferring to keep their army centralized. But without a garrison keeping an eye on them, the tributary cities had to have a strong incentive to live up to the requirement to keep supplies stockpiled. Much of this incentive was provided by the Aztecs' quite bloodthirsty religious practices. There was a very definite implied threat that if a city failed to supply its required tribute, the city would be sacked by the Aztec army and large numbers of its citizens sacrificed to the Gods.

So basically, part of the reason the Aztec religious practices were so "hardcore" was to encourage tributary cities to stay in line and provide the demanded tribute.

Hello everyone! A friendly reminder: The mission of /r/AskHistorians is to provide users with in-depth and comprehensive responses, and our rules are intended to facilitate that purpose. We remove comments which don't follow them for reasons including unfounded speculation, shallowness, and of course, inaccuracy. Making comments asking about the removed comments simply compounds this issue. While we always appreciate feedback, it is unfair to the OP to further derail this thread with META conversation, so if anyone has further questions or concerns, I would ask that they be directed to modmail, or a META thread.

So, before you try your hand at posting, check out the rules. Please consider this a warning to NOT post comments you know will be removed. Thank you!