Human Soulism

Human Soulism is the ideological representation of the Human Souls from the Indie Game Undertale. The ideology entails numerous claims based around the storyline of Undertale.

The Deltarune
The Deltarune is a myth in Undertale that states that an angel will come to the Underground and make it go empty by destroying the Barrier, a magic wall that keeps the monsters stuck in the underground. This has symbolic meaning to the Player character, Frisk who has the ability to empty the underground either with violence or pacifism.

True Pacifist Run
The True Pacifist Run of Undertale is a specific run of the game where you intentionally do not kill anyone, and befriend everyone (Non-Boss Monsters optional). To do this run you need to go on three dates with Papyrus, Undyne, and Alphys, and when you finish the Alphys date you can go back to the Lab in the Hotland region, you may go into an area underneath the lab called the True lab which holds a difficult area where you learn about Alphys' past experiments with a substance known in universe as Determination. Upon you going to end the run, every monster in the game will show up to give you praise and aid against Flowey, a character who is important to the game. It is said that every monster soul in the entire underground is equivalent to a singular human soul, which Flowey takes advantage of by taking the 6 Human Souls which have been taken by Agore over the decades, but also the souls of all monsters, becoming his true form, Asriel, who is the late son of Toriel and Asgore. The run ends with Asriel shattering the barrier and everyone going free to the above world.

Determination
Determination is the substance in Undertale which allows Human souls to persist after death, although it is lesser in the other souls, Frisk has a red soul which is the soul of Determination. Determination is also theorized to be the reason why Frisk is able to Save and Load, as their determination is thought to control the timeline(s) that they inhabit.

Alphys' Experiments
Alphys experimented with a substance called Determination to see if they could make a monster close to death stay alive longer. Monsters in universe are described as being made of almost entirely magic instead of physical matter, Determination as a substance is essentially only feasible to be added to physical beings like Humans. The monsters in the True Lab were injected with Determination which caused their magical forms to melt, which while preventing death, made many of the monsters fuse into abominations that she hides in the essential Basement of her lab.

Genocide Run
The Genocide Run is the secondary path to the Deltarune Theory. This path is where the player kills every single monster until there is no more in a given area. The player gains LV, in game referred to as Love. Your LV determines your capacity to hurt, the more you hurt the easier it is to hurt, which explains your damage increase the more you kill. The end of the run has you slaughter the King, Asgore and then having his soul destroyed by Flowey, who you then slaughter, ending the run, which allows you to destroy the world with meeting the entity Chara, a late adoptive child of Toriel and Asgore, who is awakened by your determination levels.

The Human Souls
The Human Souls are objects that have been gained by Asgore by killing several human children to take their souls in the hopes a seventh will itself fall, and he may take a final soul and become a god out of revenge for the death of his son, killed by Humans. They are useful for only two runs and do not make an appearence on the Genocide run, in the Neutral run (which asside from being the first, most different (as it has a range of endings depending on who you kill or don't kill), and the founding of the True Pacifist Run), it has little importance. It does however establish the goals of Flowey, who wishes to take your (and the 6 human souls) to become a god where he will reign over the Underground and do as he pleases.

How does this apply to ideology?
The ideology itself is a libertarian unity ideology, it believes that a person (or a main character, at least in their own life) should determine their own destiny to befriend or kill whoever they want to, with little or no consequences, aside from the battle you engage in to befriend or slaughter these people.