It can be argued that the interior of many Christian Churches, especially Catholic, Orthodox, Anglican, and Lutheran, lies in the architecture specified for the Tabernacle (The tent constructed during the Exodus) and the Temple in the old textament, where there were three area set aside for specific purposes. The area where the Altar is located in the churches I named above, especially older buildings, corresponds to the area of the Temple where the Ark of the Covenant resided, and which only the Priests of Israel entered. The main part of the church corresponds to the larger part of the Tabernacle, and the Temple, where the faithful gathered, and the foyer corresponds to the outer court, which was open to a larger number of people.
In a Christian church, the other elements of the architecture provide focal points to call the attention of the faithful to the sacraments, hence the presence of the Baptistry, or baptismal font, and location at which the Mass or communion is celebrated. In a Roman Catholic church, the location in which the Body of Christ is housed is supposed to be front and center, and in the churches I named above, a Cross or Crucifix are always present to call to the viewer's mind the salvific acts of God. Roman Catholic, Orthodox, and to a somewhat lesser extent, some Anglican and Lutheran buildings will contain representations intended to call to the viewer's mind members of the community of the faithful departed by icons, stained glass windows, or statues, including Mary, the Mother of God, the Apostles, the Mighty Acts of God, including creation, perhaps the Flood, or the other sacraments or rites. One thing all of the churches have in common (and most other protestant ones as well) is a pulpit or lectern in a prominent place, from which the word of God can be proclaimed.
These elements have been interpreted in different ways by different architects, and by different theological emphases of various Christian groups, at different times, and in different places, taking to account local materials and customs.