Gerald Gardner in the context of "Gardnerian Wicca"

Wicca (English: /ˈwɪkə/), is a modern pagan, syncretic, Earth-centred religion. Considered a new religious movement by scholars of religion, the path evolved from Western esotericism, developed in England during the first half of the 20th century, and was introduced to the public in 1954 by Gerald Gardner, a retired British civil servant. Wicca draws upon ancient pagan and 20th-century Hermetic motifs for theological and ritual purposes. Doreen Valiente joined Gardner in the 1950s, further building Wicca's liturgical tradition of beliefs, principles, and practices, disseminated through published books as well as secret written and oral teachings passed along to initiates.

Many variations of the religion have grown and evolved over time, associated with a number of diverse lineages, sects, and denominations, referred to as traditions, each with its own organisational structure and level of centralisation. Given its broadly decentralised nature, disagreements arise over the boundaries that define Wicca. Some traditions, collectively referred to as British Traditional Wicca (BTW), strictly follow the initiatory lineage of Gardner and consider Wicca specific to similar traditions, excluding newer, eclectic traditions. Other traditions, as well as scholars of religion, apply Wicca as a broad term for a religion with denominations that differ on some key points but share core beliefs and practices.

Witchcraft Today is a non-fiction book written by Gerald Gardner. Published in 1954, Witchcraft Today recounts Gardner's thoughts on the history and practices of the theoretical witch-cult, and his claim to have met practising witches in 1930s England. It is based on the discredited Witch-cult hypothesis which argued that persecuted witches had actually been followers of a surviving pagan religion. It also deals with his theory that the Knights Templar had practised the religion, and that the belief in faeries in ancient, mediaeval and early modern Europe is due to a secretive pygmy race that lived alongside humans. Witchcraft Today is one of the foundational texts for the religion of Wicca, along with Gardner's second book on the subject, 1959's The Meaning of Witchcraft.

Gerald Gardner in the foreword to Witchcraft Today:

Doreen Edith Dominy Valiente (4 January 1922 – 1 September 1999) was an English Wiccan who was responsible for writing much of the early religious liturgy within the tradition of Gardnerian Wicca. An author and poet, she also published five books dealing with Wicca and related esoteric subjects.

Born to a middle-class family in Surrey, Valiente began practising magic while a teenager. Working as a translator at Bletchley Park during the Second World War, she also married twice in this period. Developing her interest in occultism after the war, she began practising ceremonial magic with a friend while living in Bournemouth. Learning of Wicca, in 1953 she was initiated into the Gardnerian tradition by its founder, Gerald Gardner. Soon becoming the High Priestess of Gardner's Bricket Wood coven, she helped him to produce or adapt many important scriptural texts for Wicca, such as The Witches Rune and the Charge of the Goddess, which were incorporated into the early Gardnerian Book of Shadows. In 1957, a schism resulted in Valiente and her followers leaving Gardner in order to form their own short-lived coven. After investigating the Wiccan tradition of Charles Cardell, she was initiated into Raymond Howard's Coven of Atho in 1963. She went on the following year to work with Robert Cochrane in his coven, the Clan of Tubal Cain, although she later broke from this group.

Wiccan views of divinity are generally theistic and revolve around a Goddess and a Horned God, thereby being generally dualistic. In traditional Wicca, as expressed in the writings of Gerald Gardner and Doreen Valiente, the emphasis is on the theme of divine gender polarity, and the God and Goddess are regarded as equal and opposite divine cosmic forces. In some newer forms of Wicca, such as feminist or Dianic Wicca, the Goddess is given primacy or even exclusivity. In some forms of traditional witchcraft that share a similar duotheistic theology, the Horned God is given precedence over the Goddess.

Some Wiccans are polytheists, believing in many different deities taken from various Pagan pantheons, while others would believe that, in the words of Dion Fortune, "all the Goddesses are one Goddess, and all the Gods one God". Some Wiccans are both duotheistic and polytheistic (and sometimes a combination of duotheism, polytheism, and pantheism) in that they honor diverse pagan deities while reserving their worship for the Wiccan Goddess and Horned God, whom they regard as the supreme deities. (This approach is not dissimilar to ancient pagan pantheons where one divine couple, a god and goddess, were seen as the supreme deities of an entire pantheon.) Some see divinity as having a real, external existence; others see the Goddesses and Gods as archetypes or thoughtforms within the collective consciousness.