Split on two levels, on the ground floor we find the administrative and social areas, including a parish centre, whereas on the upper level, the loftier space inside the cylindrical volume is reserved for the church hall. The technical and storage areas are relegated to a small basement while the building's lift and two staircases are housed in the corner towers.

Accommodating up to 126 worshipers, the circular church hall features a suspended square surface that mirrors the seating area underneath and softly diffuses the daylight flooding in from the clerestory windows whilst also concealing the ventilation equipment. Fittingly, this simple geometric composition, a square superimposed on a circular plan, is the inverse of the one taking place outside where the cylindrical volume is superimposed on the building's square footprint.

The hall opens up to a semicircular side chapel housing the baptismal font with an adjacent semicircular apse containing the image of the Virgin and the tabernacle, and a second chapel where the crucifix stands, all three ceremoniously day lit by either indirect lighting or by targeted skylights. Situated diagonally from the stairs that lead the worshipers into the church, the crucifix not only becomes the focal point of the congregation area but also determines the orientation of the seating rows.

The immersive atmosphere of sacredness that the ethereal use of daylight achieves is enhanced by the all-white interiors, a mix of white concrete and off-white marble for the floors and wainscoting. The enveloping white palette is only tempered by the natural hues of the wooden bespoke furniture of modernist simplicity that can be found throughout the building gracefully complementing the cool marble surfaces with their warm tactility.

Being the first new church in Brittany in the 21st century, Saint-Jacques-de-la-Lande re-interprets the modernist ethos with contemporary pathos to create a place of enduring spirituality.