Since we haven't managed to decipher the Minoan's script, we don't know all that much about their religious customs. We do know some things based on physical remains, however. There are figurines of goddesses holding snakes, a lot of ceramic and painted bulls, and a lot of double-headed axes. So, it's pretty certain these were important symbols to them. There have also been a few shrines found in caves, so that's something.

The Greeks also mentioned later Cretain deities, who may have been related to earlier Minoan deities. One of these is named Britomaris, AKA "the good virgin." She seems to have been similar to Artemis in some ways, enough for the Greeks to feel they were equivalent. It has been theorized that the snake-wielding figure I mentioned before is Britomaris.

In regards to the Mycenaeans, we know a great deal more due to having deciphered their script. Mostly, this gives us names of gods and goddesses. As you might have suspected, they were pretty much the same as the ones the Classical Greeks worshiped! There were some differences, however. They didn't worship Apollo or Aphrodite, which lends to the suspicion that they were adopted from Eastern cultures. They also seem to have given a greater preference to Poseidon than Zeus. Interestingly, they DID worship Dionysus, even though some Classical Greeks believed he had come rather recently from India.

There isn't much indication of HOW they worshiped their gods, but they likely sacrificed in ways that were similar to their decendents. It's worth noting that the Myceneans made mention of Persephone and Demeter, and seem to have given them great importance. This lends credence to the later idea that the Eleusinian Mysteries, a mystery cult that involved those two goddesses, was VERY ancient.

For Minoan religion, I highly recommend checking out this page maintained by Jeremy Rutter at Dartmouth. It's what we used in my graduate Aegean Archaeology class and I used it myself a lot elsewhere as well. I only caution you to remember that because our understanding of Minoan religion comes almost entirely from archaeology, it suffers from all the usual caveats and vaguaries of archaeological preservation. Thus, when Rutter says things like:

A survey of the representational art which illustrates Minoan religious activities clearly indicates that those figures which are plausibly to be identified as divinities rather than as mortals are overwhelmingly of the female sex.

It should really say that "a survey of the extant representational art..." While we see a lot of goddesses and relatively few gods in what we've found, it's entirely possible that male divinities were worshipped in ways that do not preserve as well in the archaeological record, and so their importance or abundance is underrepresented in our understanding of it.

RELIGION IN MINOAN CRETE

Crete’s Religious Context The religious structure of Minoan Crete is one preoccupied with that of the divine. The Minoan world, as it stands through historical understanding of archaeological sources, shows plentiful traces of an organised belief system that was prominently integrated into the society and lives of its people. The extent to which historians can currently examine the nature of the Minoan belief system relies in interpretation of specific religious artefacts, layout of archaeological sites, and the Minoan A and Mycenaean B tablets, though there are few of the former. The conception of a functioning Minoan belief system has revolved around the similarities evident between the Minoans and Myceneans. Like many bronze-age societies, the Minoan religious system revolved around the belief in a number of divinities that shaped the natural and environmental world around them. These integrated themselves into Minoan society and their practitioners seamlessly – so closely, Hood notes, ‘It is often difficult to distinguish representations of gods from those of their priests and worshippers.’ Minoan Deities It should be noted that, like any historian working in a field of contentious debate, the evidence relating to the identity of the deities and their nature in the Minoan system remains ambiguous at best.

PONTIA

Central to the spiritualistic Minoan religious system was ‘Pontia’, addressed in Linear A as a possible ‘mother goddess’ figure – although this could also be Demeter, referenced in Linear A. She possesses heavy symbolism within many shrines and sanctuaries – referred to as the ‘Lady of the Labyrinth’. Based upon the cultural exports of Crete we find Pontia on Mainland Greece – theories about the transformation of Pontia into Athena continue to this day. Pontia was only one part of a vague polytheistic system, but it is purported by Castleden that ‘the double-axe was Pontia’s symbol, and possibly the pillar and snake too’. The labrys, or double-axe, was most certainly a symbol of the Labyrinth, having its symbolism strongly integrated into the architecture of palatial and temple areas at Zakros and Knossos. Perhaps it is even illustrative of the Minoan minotaur legend which has permeated the imagination of Evans and other traditional historians for years. Fundamental to Minoan religious symbolism is that of the snake and pillar – the ‘pillar worship’ of Crete in homes and villas can be seen as representative of the Cult of a mother goddess, or that of a sacred tree and naturalistic symbol of life. The Knossos Gg Tablet addresses ‘Pontia of the Labyrinth’ – it is possible this goddess had labyrinthine sanctuaries in other Minoan temples.

KOUROS

Kouros is a figure whom seems to have been indicative of a cyclical system of death and resurrection in nature. This figure, dubbed a ‘year-spirit’, is portrayed by a masculine figure called ‘Kouros’ – depicted in two ivory figures of pubescent figures Evans remarks most likely came from the Labyrinth and temple in Knossos. Kourous is evidently believed by Hood to depict ‘the death and resurrection of a god of vegetation, central to the cult of the goddess (Pontia)’. This god is subsequently believed to have been a predecessor of Zeus – even transforming in the late period as ‘Zeus Velachos’. Alexiou, however, reminds us that there may have been many other ‘divine boys’ present in Minoan worship. However, it is likely that the depiction of young men in some Minoan frescoes may have been that of Kouros.

SEA WORSHIP

As a civilisation closely connected to coastal life and trade it seems natural that Minoan Crete fixated itself upon the system of deities connected to the ocean. A number of historians have hinted at the presence of a ‘sea goddess’, but little is known about the nature and practice of sea worship – Castleden purports this is as coastal shrines on the shore would have been too vulnerable to be preserved today. The Ring of Minos is one indication of the imagery of the sea in ritual worship. It portrays a priestess carrying ‘portable shrines’ across the ocean to different temples. This is consistent with beliefs concerning Minoan Crete regarding the nature of ‘seashore cults’ in which ‘deities were transported in ships to describe a magic circle of divine protection around the island’. Willetts purports that ‘leaping’ into the sea' may have been an initiatory practice reminiscent of Minoan myth.

POTIEDAN

It is possible that Potiedas or Poteidan may have been present as the Greek Posiedon in Crete as large-scale votive and sacrificial offerings at Pylos during the Mycenaean period were offered in his name. Castleden suggests it is a possibility this practice spread to Crete. However, it is certain that Poteidan was a religious figure whom merged a number of iconographies in his worship – Potiedan is referred to in many tablets as the ‘Bull God’ or the ‘Sun God’ – and it is in this form that Potiedan has been concluded to act as an all-powerful figure whom could take a number of manifestations. Potiedan’s most prominent manifestation is that of the bull – a figure that permeates the rituals and arts of Crete to an extent that it is difficult to construe the meaning of ‘bull leaping’ and the practices which typified Potiedan worship. Thus the symbolism of bulls and also horns, most notably that of model bulls and horns of consecration appear in a number of places. This is postulated by Nanno Marinatos as a symbol of ritual bull sacrifice – having been found in monumental scales at Knossos.

THE SNAKE AND DOVE GODDESSES

Our knowledge of the snake goddess is both derivative of the source of information on Pontia, and that of two faience snake-wielding figures from Knossos. The symbolic significance of snakes has many meanings: possibly as a symbol of immortality (the ‘shedding’ indicative of rebirth) or life within the earth. The Snake Goddess herself is seen to be the host of one of the largest Underworld cults on Crete. Like many deities, her physical affinity with the animal (snake) world substantiates that she is a goddess, much like that of the Dove Goddess found in sanctuaries at Knossos – in this case figurines found in sanctuaries at Kannia portray both doves and snakes. The symbolism of doves has been interpreted to relate to the value of fertility. The depiction of goddesses with doves is standard in many shrines and sanctuaries, and these figures often are depicted in a pose in which their arms are raised: most likely a customary manner to denote prayer or divinity. Examples of this are present with the Dove Goddesses in the Knossos Shrine of the Double Axes, and the Goddess with Her Arms Raised at Gazi, Herakleion. Sites of Worship The Minoans expressed the practice of worship in certain areas, but shrines – the basis for Minoan votive offerings and libations which served as the basis for personal worship – have been found in public and private spaces in Crete.

CAVE AND PEAK SANCTURARIES

Across Minoan Crete there existed a large number of caves and peak enclosures in which religious sanctuaries were established. These were used fundamentally as ‘dwellings from the earliest time of habitation, then as burial-places, shrines and sancturaries’. Not only did these serve as the site of worship for cults, but even for the secret or underground revival of old rituals and gods – though at 2000 BC this was replaced in mainstream Crete by the prominence of temples in the civic structure. The amount of food found within the sites of these peak shrines, as well as vases for libation and figures of model animals and men substantiate a system of pilgrimage – the largest of the sanctuaries on Mount Juktas having areas for storage of offerings around the shrine and ritual fires. Of course, the symbolism of earth, sky and sun would have been a focal point to these.