Mjölnir in the context of "Thor's Fight with the Giants"

Old Norse religion, also known as Norse paganism, is a branch of Germanic religion which developed during the Proto-Norse period, when the North Germanic peoples separated into distinct branches. It was replaced by Christianity and forgotten during the Christianisation of Scandinavia. Scholars reconstruct aspects of North Germanic Religion by historical linguistics, archaeology, toponymy, and records left by North Germanic peoples, such as runic inscriptions in the Younger Futhark, a distinctly North Germanic extension of the runic alphabet. Numerous Old Norse works dated to the 13th-century record Norse mythology, a component of North Germanic religion.

Old Norse religion was polytheistic, entailing a belief in various gods and goddesses. These deities in Norse mythology were divided into two groups, the Æsir and the Vanir, who in some sources were said to have engaged in war until realizing that they were equally powerful. Among the most widespread deities were the gods Odin and Thor. This world was inhabited also by other mythological races, including jötnar, dwarfs, elves, and land-wights. Norse cosmology revolved around a world tree known as Yggdrasil, with various realms, such as Midgard, where humans live. These involved multiple afterlives, several of which were controlled by a particular deity.

Heathenry, also termed Heathenism, contemporary Germanic Paganism, or Germanic Neopaganism, is a modern pagan religion. Scholars of religious studies classify it as a new religious movement. Developed in Europe during the early 20th century, its practitioners model it on the pre-Christian religions adhered to by the Germanic peoples of the Iron Age and Early Middle Ages. In an attempt to reconstruct these past belief systems, Heathenry uses surviving historical, archaeological, and folkloric evidence as a basis, although approaches to this material vary considerably.

Heathenry does not have a unified theology but is typically polytheistic, centering on a pantheon of deities from pre-Christian Germanic Europe. It adopts cosmological views from these past societies, including an animistic view of the cosmos in which the natural world is imbued with spirits. The religion's deities and spirits are honored in sacrificial rites known as blóts in which food and libations are offered to them. These are often accompanied by symbel, the act of ceremonially toasting the gods with an alcoholic beverage. Some adherents also engage in rituals designed to induce an altered state of consciousness and visions, most notably seiðr and galdr, with the intent of gaining wisdom and advice from the deities. Many solitary adherents follow the religion by themselves. Other Heathens assemble in small groups, usually known as kindreds or hearths, to perform their rites outdoors or in specially constructed buildings. Heathen ethical systems emphasize honor, personal integrity, and loyalty, while beliefs about an afterlife vary and are rarely emphasized.

Thor (from Old Norse: Þórr) is a prominent god in Germanic paganism. In Norse mythology, he is a hammer-wielding god associated with thunder, storms, strength, protection, fertility, farmers, and free people. Besides Old Norse Þórr, the deity occurs in Old English as Thunor, in Old Frisian as Thuner, in Old Saxon as Thunar, and in Old High German as Donar, all ultimately stemming from the Proto-Germanic theonym *Þun(a)raz, meaning 'Thunder'.

Thor is a prominently mentioned god throughout the recorded history of the Germanic peoples, from the Roman occupation of regions of Germania, to the Germanic expansions of the Migration Period, to his high popularity during the Viking Age, when, in the face of the process of the Christianization of Scandinavia, emblems of his hammer, Mjölnir, were worn and Norse pagan personal names containing the name of the god bear witness to his popularity.