Heathen groups are typically called kindreds or hearths, or alternately sometimes as fellowships, tribes, or garths. These are small groups, often family units, and usually consist of between five and fifteen members. They are often bound together by oaths of loyalty, with strict screening procedures regulating the admittance of new members. Prospective members may undergo a probationary period before they are fully accepted and welcomed into the group, while other groups remain closed to all new members.

In Heathenry, moral and ethical views are based on the perceived ethics of Iron Age and Early Medieval Northwestern Europe, in particular the actions of heroic figures who appear in Old Norse sagas. Evoking a life-affirming ethos, Heathen ethics focus on the ideals of honor, courage, integrity, hospitality, and hard work, and strongly emphasize loyalty to family. It is common for practitioners to be expected to keep their word, particularly sworn oaths.

As part of the Norse cosmological framework, humanity's world—known as Midgard—is regarded as just one of nine realms, all of which are part of a cosmological world tree called Yggdrasil. Different types of being are believed to inhabit these different realms; for instance, humans live on Midgard, while dwarves live on another realm, elves on another, giants on another, and the divinities on two further realms.

Heathenry is usually characterized as being polytheistic, exhibiting a theological structure which includes a pantheon of gods and goddesses, with adherents offering their allegiance and worship to some or all of them. Some practitioners are polytheistic realists, insisting in the literal existence of the deities as individual entities. Others express a psychological interpretation of the divinities, viewing them for instance as symbols, Jungian archetypes or racial archetypes, with some who adopt this position deeming themselves to be atheists.

The All-Father or  Alföðr was not the supreme god in Norse mythology. Odin was the earliest common ancestor that all members of Norse society could trace their lineage back to. The veneration of Odin was most likely practiced because Norse society was comprised of consanguineal corporate groups that had strong family lineages whose continuity, standing, and control of resources extends over generations, and in which there were strong beliefs in an active spirit world.

Ancestor worship is a religious form of worship which emphasizes the influence of deceased relatives on the living. The veneration of ancestors is not a religion in and of itself, but a facet of religious expression which recognizes an element beyond human control. This form of worship is at the core of the Old Custom (Forn Siðr). Consequently, the old Norse religious custom specifically, and the even older Germanic customs more generally, were not the polytheistic traditions that monotheistic-based scholars suggest. 

When Christianity first entered the Nordic regions, the Norsemen did not have any particular name for their religious practices. To set those old practices apart from the new Christian tradition, Christianized Noblemen began to refer to their ancestral practices as the Old Custom (Forn Seiðr), which in popular culture is usually expressed as the Old Ways.