- Communion table, most often called the altar.
- Communion railing, also called the chancel railing, with provisions for kneeling.
- Pulpit, used by clergy for gospel readings and sermons.
- Lectern with Bible, used by lay readers for scripture readings.
- Boundary between nave and sanctuary; usually the floor of the chancel is three steps higher than the floor of the nave.
In Orthodox churches, the boundary is an iconostasis. Any lecterns are in front of the iconostasis, placing them in the nave instead of in the chancel, as in western churches.
- Congregation. Western churches have pews, but in most Orthodox churches the congregation still stands.
- The sanctuary or chancel.
- The nave, where the congregation sits
Note that in some churches, the architect may have swapped the positions of the lectern and the pulpit for aesthetic reasons or because of the layout of the rest of the building.
The choir may be located behind the chancel, to one or both sides of the chancel, behind the congregation, or on a balcony behind the congregation. The church floor plan may include a transept, a rectangular area between the chancel and the nave that is wider than the rest of the building. (As a result, the church is shaped like a cross when viewed from the air.) The choir might be located in the ends of the transept. The choir is positioned so that it can be heard, without consideration for its visibility. The transept is a medieval architectural innovation.
After the congregation is seated, the choir, lay leaders, and clergy (in that order) enter in a procession up the aisle. The minister who delivers the sermon sits near the pulpit. There may two seats within the chancel railing, one for the minister who conducts the communion and one for a lay helper. Leaders generally face the communion table when addressing God, whether in prayer or song, because they are acting as part of the congregation. Leaders face the congregation only during announcements, scripture readings, and the sermon.
The basic elements of this floor plan come from the layout of first-century house, because the earliest Christian churches were house churches. The ancient institution of the household included the functions of modern families and businesses; you could say that the household was a family business. When visitors came to the house to do business with the household, they would come through the front door into a very large room with little furniture. At the opposite end of the room was the family dining room on a raised floor. It had a chopping block front and center. (The private rooms for members of the household were behind the dining room.) The father sat against the back wall of the dining room behind the chopping block, and his sons sat against the wall on either side. The sons conducted the actual business under the father’s supervision. When the building became a church, the atrium became the nave, the dining room became the chancel, and the chopping block became the altar. The bishop sat in the father’s place and the priests sat in the sons’s places. Ancient Christians found a glorified version of their church’s floor plan in Revelation 4:2-4. In this passage, the throne in the middle is the altar, the 24 elders sit in a circle around the throne instead of in a semi-circle behind it, and Jesus, in the role of the bishop, sits on the altar instead of behind it, because He is also the sacrifice.
A modern church with this floor plan and a congregation of about 100-150 is as close as you can get to a New Testament house church.
With local variations, this floor plan is used by Orthodox, Roman Catholic, Anglican, Lutheran, and Methodist churches, among others. Many Roman Catholic churches have a semi-circular nave that surrounds the chancel, for a theater-in-the-round effect. Surprisingly enough, this is not a contemporary innovation; it goes back at least to medieval times.
In western churches, the congregation has a speaking role in the service; that is, the clergy lead the congregation, who actually perform the bulk of the service. This makes the service seem complex to the first-time visitor. The first part of the service emphasizes Bible readings and the sermon, and it follows the general plan of a synagogue service. The second half of the service, if present, consists of communion. Any part of the service, except Communion, may be led by a lay person. Most Bible readings and prayers are offered by lay leaders. The gospel reading and the sermon are generally done by clergy. The congregation generally stands to sing or respond, sits to listen, and kneels to pray. Everyone does the same thing at the same time, so it looks regimented to an Orthodox visitor.
Orthodox churches follow the same plan, except that there are generally no pews and often the entire service is sung responsively by the clergy and the choir. The role of the congregation is to stand in awe and prayer. Seats are provided for the disabled. Individuals in the congregation are allowed to come and go when they like, walk around, bow, stand, light candles, kiss icons, and so forth, during the service. It looks chaotic to a western visitor. Orthodox worship has not changed at all for over 1,000 years.