Due to lack of writing style of the ancient people of Gaul, the ancient Celtic religions and practices are primarily lost to society.

The ancient people of Gaul were practitioners of polytheism, often resulting in small tribes and regions venerating one primary god such as Cernunnos, Epona or the Dagda. The deity chosen to protect or represent a tribe or region would often be one which would represent the lifestyle of the people. Peoples who would find themselves often at war would more than likely pray to a god like Taranis while those who were closer to the ocean would more than likely pray to a sea faring god like Epona.

It is through people like Julius Ceasar that we have most of our oldest testaments to the ancient Celtic people. During his invasion of Gaul, he wrote much on the practices of the Druid people and other people in the area as well as their gods, though often only in comparison to more contemporary Greek deities. An example of this is the comparison of the Celtic goddess Brigit, God of Fire, Fertility, Healing, Cattle and Poetry, to Vesta or Minerva.

Through the burial practices of these ancient peoples, we can conclude that they believed in an afterlife. In the burial sites found in what was once the Gaulish region of Europe there have been numerous kinds of burial goods found such as weapons, food and ornaments.

There are numerous instances of sacrifices and offerings found as well including many votive offerings, temples, and animal and human sacrifices. A distinct aspect of temples found in modern day United Kingdom is that they are circular in shape in comparison to the square or rectangular shaped temples found in modern Bavaria or Burgundy. Votive offerings given by this group of people were often buried in bogs or thrown into water features such as a lake, river or the sea. Animals sacrificed were typically buried very carefully as to protect the properties that would please the intended god the most. Evidence of human sacrifices suggest that they took place in large wicker constructions that were then set on fire. In some instances, it was only a human in these structures but in others there is evidence showing that there were animals included in these practices as well.

Christianization of the Celtic people ended the practices of ancient Celtic paganism in Gaul in the 5th century CE. The year typically used to mark this date is 410 CE, the year in which Roman rule in modern day England ended and the conversion to Anglo-Saxon way of life began.

While many modern practitioners of Celtic worship would argue that the Celtic way of life is significant only to those who descend from the English islands and Ireland, this would be dismissive to the actual definition of Celtic which includes a majority of mainland Europe as it is less relevant to a group of people and more in reference to the language spoken by these people which spread far into the area of modern Europe including but not limited to Normandy, Germany, Burgundy, Bavaria, France, Scotland, Ireland and England.

Practices of modern Celtic worship include but are not limited to Druidry, Wicca, Celtic Reconstructionism and Eclectic Paganism. Many practices within these religions are lost to history but there are basic practices which have survived the test of time such as rune reading, the Ogham alphabet, Celtic cross Tarot reading, various holidays and altars and offerings in dedication to either a venerated god or ancestral worship.

Most of these practices are not directly derived from the beliefs of the ancient Pagans who created them but instead taken with interest in making them more appropriate to the modern world. Animal and human sacrifices are no longer part of Neopagan practices and coven practice is the least common form of worship found in Paganism.

Holidays are one of the largest ways in which the ancient practices of Celtic Pagans survive in the modern day with fire festivals being very popular among the current generation of practicing Pagans.

The oldest calendar of the year known to have been used by the Gauls and other practitioners of Celtic paganism is the Coligny calendar. It is believed that ancient people like the druids would have used this calendar to track the days and holidays as well as feasts, seasons and festivals.

Most modern practitioners of Celtic worship and the various branches of Neopaganism which would fall into said category use the Wheel of the Year. The holidays found on the Wheel of the Year are in alignment with major astronomical events, such as equinoxes and solstices, or the harvest season.

The holidays recognized in the Wheel of the Year are as follows:

• Imbolc (February 1)

• Ostara (March 21)

• Beltane (May 1)

• Litha (June 21)

• Lughnasadh (August 1)

• Mabon (September 21)

• Samhain (October 31)

• Yule (December 21)