After much argument we both agreed that each building type has an essence that must be present. Without this "essence" the building could very well be mistaken for a factory, a commercial building, and so on. In the case of a church building the essence is its "sacredness".
We first talked about Catholic churches. The layout of Catholic churches have changed in the course of history, from theocentric to anthropocentric. In the search for openness and "oneness" the altar had been moved from the back to the center, the sanctuary is now at the same level as the populo, the communion rails removed, and so on. Despite the changes the church retains its sacredness. But precisely what is it that is sacred in a church?
To answer this we discussed different sacred structures outside of the Catholic churches. We tackled eastern churches like Angkor Wat, or modern places of worship like the ones designed by Tadao Ando. In the end we realized that the thing which is sacred is not a physical object but something intangible, in fact, it is the idea of achieving the presence of God, or Allah, or the supreme or Holy Being.
We can use pictures to remind us of who we worship. We can use objects like crucifixes and other symbols. It could also be our interpretation of the teachings which we try to reflect in architecture. It is so varied. Each one has his own sense of what is sacred. But being a social being, this sense of what is sacred can be shared and can be common to a group of men or community, bounded by culture or other values. Thus a native tribe can create a worship space which they see as sacred but the modern man might never understand.
With this in mind it would be easy for any architect, regardless of religion, to design a worship area to anyone. There must be a research involved to determine the client's idea of what is sacred. The client here is not necessarily a single person, in fact, it should be the worshippers of a particular area. Even among Catholics the idea of what is sacred can differ.
Architecture students should be trained early on in becoming sensitive to these matters. The church is just one building type that we considered in our discussion. It would be interesting to tackle a school, a home, and other building types as well.