In the three cultures we have so far studied - Roman, Mediæval and Muslim, how did /does the garden play a role in their respective religions?

Roman

The Roman Empire was one of the most widespread and influential societies to day. The empire lacked a complete separation between church and state, making religion a key part of everyday life, including in terms of gardens and their designs. While many features of Roman gardens were practical (such as water features used to cool the surroundings) or aesthetic, several features had important religious significance. There were typically shrines or statuary paying respect to specific gods and goddesses, many of whom had been taken from the Greek Empire. These came in many forms, including a nymph-shrine water feature (Aedicula), and frequently the herm (a statue comprised simply of a head, column, and genitalia). Plants were also used in symbolic religious expression for the Romans.

http://openbuildings.com/buildings/chiswick-house-profile-6502

Mediæval

In the Mediæval era, there was a strong emphasis on original sin and salvation through the Church, which was reflected in the garden art of the time, with the Church having a large level of influence. The Church created the Mediæval monastery, which was utilitarian and practical, with a driving purpose of self-sufficiency. These monastic gardens were primarily function, but had symbolism, through the cloister and paths symbolizing the four rivers leaving Eden. Additionally, there was a separate type of garden in the Mediæval era, known as Hortus conclusus, or the Mary gardens, which were more ornamental with symbolism both in concept and in plant selection of the Virgin Mary.

http://imgarcade.com/1/medieval-garden/

Muslim

The gardens of Islam were aesthetically very different from those of the Roman and Mediæval eras, although they also included a significant level of religious symbolism. In the Islamic religion, heavy emphasis was placed on creating beauty as a form of reverence. There was also stress on inner richness of beauty with a humble outer appearance, which was reflected in the closed, humble outer confinements of gardens. The Qur’an acted as a blueprint for garden design, and gardens were meant to be representations of Paradise after life. Water features played an essential symbolic role, with four incorporated as the four rivers of life. The four garden beds defined by the water features, known as chahar bagh, represented the earthly paradise.

http://lifeinstillmode.blogspot.dk/2012/03/indian-char-bagh-garden.html

In all three eras studies thus far, symbolism in the garden was a direct reflection of religious beliefs, and allowed for a guided expression of religion in an aesthetically pleasing form.

The following website discusses further examples of religious garden art in different cultures:

http://www.gardenvisit.com/history_theory/garden_landscape_design_articles/sacred_gardens