There are indeed good reasons why the architecture of the earliest monumental church buildings differed significantly from the temples of Pagan religions. For one thing, it was simply not in the interest of the early Christians for their places of assembly to resemble those of other cults. In the eyes of Christians, the religions of Greece and Rome were characterized by idolatry, demonic worship and bloody sacrificial rituals, things they wanted to have absolutely no part in. It would not have made sense to imitate the buildings where all this was practiced.

Polemics aside, the early Christians were not necessarily far off the mark here. The way in which the Pagan cults were practised was indeed very different from Christian worship and this was also reflected in the design of the religious architecture of both groups. Let us first have a look at what a Greco-Roman temple actually is and what it isn’t. It certainly wasn’t a place for large groups of people to congregate and worship together. Instead it was simply a shrine to house the cultic image of a god, more a very elaborately designed container than a building to be used and visited by people. The actual worship didn’t take place inside of it. Instead that was performed at an altar in front of the temple, were the sacrifices took place. Those were the central acts of religious practise for the adherents of the Pagan cults. This first century AD wall painting from Pompeii visualizes that relationship rather well. In the front a priest of the Isis cult is performing a sacrifice at an altar while the cult image (a sarcophagus of Osiris with Horus falcon) looks on from within what seems to imply a kind of temple building.

This means that a temple wasn’t even a necessary component to every sanctuary. The only essential part was the altar. Sacrificial rituals didn’t need to take place in front of a large temple, they could also be performed in a sacred cave, at a street crossing or inside one’s own house.

How did this influence the architecture of Greek and Roman temples? For one thing not nearly every one of them was as monumental as the Parthenon in Athens or the temple of Jupiter Optimus Maximus on the Capitol in Rome. They could also be tiny shrines, just large enough to house the cult image and without much space to even enter it. If they were built larger it wasn’t to be able to house more people but to give a god a suitably grandiose home. Consequently most temple interiors are architecturally relatively simple. For example the cella of the Maison Carrée at Nîmes is just a rectangular space with the entrance at one side and the cult image at the other. Of course those interiors could still be lavishly decorated, they should be a suitable home for a god after all. But the visually most interesting part was almost always the outside, because that was what people saw when stood at the altar. Much thought and skilful work went into its design. They were surrounded by rows of carefully drafted columns, decorated with intricately carved friezes and reliefs and bore monumental inscriptions. The features most prized about the Athenian Parthenon are its elegant proportions and the incredible skill that must have went into producing the curvature of the entire building. The splendid sculptures housed in the British Museum were once decorating the Parthenon’s tympanon. All this was visible from the outside.

Such a building would have been of absolutely no use to the early Christians. Their religion didn’t have any sacred images yet – idols as they would call them – and they were very insistent upon that fact. The cult of Christian icons or devotional pictures would only come into being much later, when church architecture had already centuries of history. So to the early Christian religion a building to house a sacred image was simply obsolete. Their religious practice revolved around gathering the congregation to listen to the holy texts and most importantly take part in the holy communion at the eucharist. Their altar was no place for bloody sacrifice but where they commemorated the most important sacrifice of all: the crucifixion of Jesus Christ. And since only people who had already been baptized could take part in that the altar couldn’t be placed outside where everybody would have been able to access it. So what Christians needed were spaces for communal gatherings. Inside the Roman architectural canon the building type that came closest to serve this purpose was the basilica. Structures like the Basilica Ulpia at the Forum of Trajan in Rome were designed to house large groups of people. The long rows of columns made it possible for the interior space to be even larger while still supporting a roof over it. People could do business here or settle their legal matters. Since they entered for different reasons and did not all take part in the same activities most civic basilicas lack a singular architectural focal point. You often entered them from their broad side and then could go wherever you liked. The new Christian basilicas needed to be different in this regard. Everyone in there was here for the same reason: to listen to the same texts and watch the same liturgy. So the entrance was at the far side directly opposite to the altar, which in most cases was accentuated by an apse behind it. The long rows of columns now visually emphasized the way from the entrance to the altar. Rome’s Santa Sabina still gives a remarkably good impression how those early Christian basilicas looked like.

The strong focus on the interior was reflected in the decoration of those churches as well. From the outside they were deliberately designed to be rather plain looking. Santa Sabina is representative of this as well. The feature that stands out the most are the large windows, which provide light for the inside. Decorations like reliefs, friezes or marble revetments are rarely to be found at late antique church facades. The interior was a whole other story though. Here colourful marbles, shining mosaics and splendid wall paintings abounded. The gathering room of the Christian community was staged as a privileged space, deliberately differentiated from the outside.

Nevertheless the basilica form was still relatively simple. To produce more spectacular interior spaces Late Roman architects had a different option: central-plan buildings topped off by large domes. Such domes were very rare among ancient temples (the Pantheon in Rome is spectacular and rightfully famous but also highly unusual). But among the monumental churches of Late Antiquity they are much more common. Constantine the Great already chose a central-plan building when he donated a new church for the city of Antioch at the Orontes, the so called ‘Golden Octogon’. The most remarkable feature of Istanbul’s Hagia Sophia, maybe Late Antiquity’s most famous church, is its dome. Their popularity is easy to understand. A dome develops its optical effect primarily inwards and makes for a spectacular setting for the Christian liturgy.

It’s only much later that ancient temple designs would be used as models for church buildings. After the Pagan religions of Greece and Rome had largely died out the temples stopped being symbols of idolatry and started to be associated with Rome’s lost glory that most Christian societies tried to emulate in some way. This explains churches like the 7th century ‘Tempietto sul Clitunno’ or the 18th century Panthéon in Paris.

I hope I can help in this. When we discuss early Christian architecture, we have to consider that church’s in the this period were places of power, designed to exhibit the strength of the individual who was patron of the build. The original basilicas of the ancient world were sites of power, places utilised by the highest individuals in society. Paul Crossley also brings up another point I’d consider essential when evaluating early church architecture: iconography is decoded in a form that is relevant to our understanding of religion; not that of the society who worshipped there. We are also reliant on extant structures for the most part - many early Christian structures were small modest chapels particularly before the rise of Christianity within the Roman Empire.

As the Roman Empire shifted to Christianity, and Christianity became a central tenant, it was natural to emulate architecture that already held symbolic power through time and in the physical space it occupied. Probably the most notable example of a Basilica in the Christian form, outside the Vatican at least, is San Vitale. It was based on the administrative chambers of Justinians palace, reflecting the centralisation of the church as part of rulers identity. These ideas were solidified in Aachen Chapel, a large structure linked to the main palace of Charlemagne. Modelled on San Vitale, Aachen was built in a early Romanesque style which is arguably the first pan-European architectural style - the relevance of this is that Christian societies in the Middle Ages attempted at least in some degree to emulate the Roman systems as it exhibited the height of power. Aachen was built consciously to dominate the city, placing the Christian religion symbolically above the population in a physical sense. The monarchy (I.e, power) was connected in physical actuality to this religious basilica by a long north south corridor linking the chapel to the palaces.

The symbolic nature of early Christian, Romanesque and later Carolingian architecture was to show the splendour of god through the material. The most splendid structures known to early Christians was the administrative structures of Rome, and this predominantly explains why they chose to utilise basilica architecture. Sources - Rollason, D.W The power of Place: Rulers and their Palaces, Landscapes, Cities and Holy Places

Stalley, R. Early Medieval Architecture (useful for Aachen)

Crossley, P. Medieval Architecture and Meaning: The limits of iconography

Camerlenghi, N The Long Duree and the Life of Buildings (investigates relationships between structures and location/space)

That's a great question, but I'd say that churches aren't just one thing or the other.

I'm going to talk about churches in Europe and England as that's my area of expertise and much of the architectural history is transferrable (with differently-named eras) across wider Europe in general.

Greek and Roman temples did contribute much to to "the standard design", by which I guess you mean medieval churches. And, for that matter, so did Basilicas.

Some features of the Basilica were very much part of large medieval churches, at least their naves. Naves were large halls with arcaded aisles, often apsidal (a curved apse/auditorium at one end), and medieval church naves were similarly a centre of communal activity outside the closed chancel. That chancel shares much with the liturgical ideas and physical layout of Greek and Roman temples - it contains holy imagery, houses a deity's form on Earth, contains an altar towards which prayer, donation or sacrifice is directed, and is largely closed to the general populace.

You and I (unless you're a very wealthy nobleperson or you've taken the cloth) would be in the nave - and the nave is very much an evolution of the Basilica in general form and intent. Where larger (or just richer) churches differ is in the symbolic layout of transepts and the extension of the apse into a full chancel. The largest churches have even more aisles and ambulatories added around them, maybe cloisters, chapter houses, vestries, sacristies, chancellories, chantries... but the working community heart of the church (and the day-to-day money-maker) remained the nave with all it's Basilica-esque origins.

Basilicas were not all built in the same architectural style due to changing tastes across regions and areas, and the same is true of medieval churches. Norman architecture was very much influenced (via Romanesque) by Hellenistic architecture and therefore shares architectural roots with many famous basilicas, but the engineering and material methods of their development differed as the technologies and ideas spread across Europe.

We now know the style as broadly "Gothic", which evolved wider, higher, arches that gave ever more light, "flying" buttresses that shared loads into external structures which still allowed light to reach even wider, taller windows, and ever-higher towers that brought man closer and closer to God.

Summary: Churches, particularly the grand churches of the early Norman period that influenced every church up until the Reformation, are based on Roman and Greek temples and architecture, and on the form and function of Basilicas.

Sources:

An Outline of European Architecture, Pevsner N, 1963 *

French Gothic Architecture of the Twelfth and Thirteenth Centuries, Bony J, 1983

French Influences on the Origins of English Gothic Architecture, Bony J, 1949

The Earth, The Temple, The Gods, Scully V, 2013

^(*Anything by Pevsner is well worth reading and buying if you're interested in the history of liturgical architecture!!!)

Hey there,

Just to let you know, your question is fine, and we're letting it stand. However, you should be aware that questions framed as 'Why didn't X do Y' relatively often don't get an answer that meets our standards (in our experience as moderators). There are a few reasons for this. Firstly, it often can be difficult to prove the counterfactual: historians know much more about what happened than what might have happened. Secondly, 'why didn't X do Y' questions are sometimes phrased in an ahistorical way. It's worth remembering that people in the past couldn't see into the future, and they generally didn't have all the information we now have about their situations; things that look obvious now didn't necessarily look that way at the time.

If you end up not getting a response after a day or two, consider asking a new question focusing instead on why what happened did happen (rather than why what didn't happen didn't happen) - this kind of question is more likely to get a response in our experience. Hope this helps!