Upright pentacles and pentagrams are among the most widely used religious symbols. They have been used in many eras and by many cultures and religions of the world: by ancient Pagans, ancient Israelites, Christians, magicians, Wiccans and others. The following pentagram-using groups are listed in chronological order:

This symbol apparently originated as the symbol of a Goddess who was worshiped over an area which extends from present-day England to Egypt and beyond. Her name was Kore (a.k.a. Car, Cara, Carnac, Ceres, Core, Kar, Karnak, Kaur, Kauri, Ker, Kerma, Kher, Kore, Q're, etc.). As Carmenta she was said to have invented the Roman alphabet. From her alternate Roman name Ceres have evolved many English words: cardiac, carnal, cereal, core, corn, and kernel. The port of Caraalis, (now Cagliari, the capital of Sardinia), was named after her. 

Kore's sacred fruit is the apple. When an apple is cut through its equator, both halves will reveal a near-perfect pentagram shape at the core, with each point on the star containing a seed. Many Wiccans, other Neopagans and Roma (Gypsies) continue to cut apples in this way. The Roma refer to the core as the Star of Knowledge.

In ancient Greece, Pythagoras (586 - 506 BCE) established a school which pursued knowledge in mathematics, music, religion, and other specialties. Driven underground, his followers used the pentagram as a secret sign to identify themselves to each other. The Masonic Order has traditionally traced its origins back 2,500 years to the Pythagoreans.

Kore was worshiped within the Coptic Gnostic Christian religion in Alexandria, Egypt, during the 4th century CE. Her festival, the Koreion, was held yearly on JAN-6. This was adopted by the Christian church as Feast of Epiphany (a.k.a. Twelfth Night). ₄ This date is still celebrated as Jesus' birthday in Armenian churches, and is observed with more pomp than is Christmas by the Greek Orthodox church. ₅  

In England, the Koreion became the Kirn - the Feast of Ingathering. The Christian church later adopted it to the Feast of Our Lady of Mercy. ₄

During the times of the Hebrew Scriptures (Old Testament), the pentacle was the first and most important of the Seven Seals - an amulet whose seals represented the seven secret names of God. It was inscribed on King Solomon's ring, which is often called Solomon's Seal in error. ₆ Each point of the pentagram was also interpreted as referring to the five books of the Pentateuch - the first five books in the Hebrew Scriptures; the Torah. 

The Celts believed that the pentacle was the sign of the Goddess of the Underground, who they called Morgan (a.k.a. Morrigan). The concept of five points seems to have permeated at least one of the Celtic lands. "Ireland had five great roads, five provinces and five paths of the law. The fairy folk counted by fives, and the mythological figures wore five fold cloaks." ₉

In Christian times:

	The five points of the pentagram have been interpreted as representing the five wounds of Christ (2 wrist, 2 ankle and 1 side).
	The Roman Emperor Constantine used the pentagram in his seal and amulet. 14
	It has been referred to as the Star of Bethlehem
	It was used to symbolize the star which allegedly led three Zoroastrian astrologers to the baby Jesus; it was called the Three Kings' star.
	The English warrior Sir Gawain, a nephew of King Arthur, adopted the pentagram as his personal symbol and placed it on his shield. 7 It appeared in gold on a red background. The five points symbolized "the five knightly virtues - generosity, courtesy, chastity, chivalry and piety." 14
	Tarot cards originally had a suit of coins or discs. These were changed in the 19th century to pentacles when the Tarot became associated with the Kabbalah. They eventually became the suit of diamonds in modern playing cards.
	It has been widely used by past Christians as a protective amulet.
	During the burning times when the Christian church burned alive or hung hundreds of thousands of innocent people, the meaning of the pentagram changed. It began to symbolize a goat's head or the devil in the form of Baphomet. "The folk-symbol of security - for the first time in history - was equated with evil and was called the Witch's Foot." 14

The religion of Wicca is based in part on ancient Celtic deities, symbols, days of celebration, etc. The pentacle and pentagram are their main symbols.