All Saints is the most beautiful of the Bourne Valley churches and is an excellent example of the Decorated style that is rare in Wiltshire. Idmiston had a tradition of remarkable stone carving and there are many good gargoyles on this flint and limestone church. The church seems to have its origins in the 12th century and the earliest part is the lower section of the tower, which is Norman. The present plain chancel was built in the early 13th century and has a piscina in the south wall of the sanctuary. In the late 13th or early 14th century the nave was rebuilt, as was the east arch of the tower. There are 37 stone corbels, one is pictured here, with well carved faces, showing many expressions, and believed to be based on contemporary villagers. An interesting selection of clothes and headwear is also depicted. There are also carved faces on the roof timbers, but these are in a poorer state of preservation. The porch and priest's room, and the two aisles are 14th century; the arcades of the latter are beautiful examples of Decorated work. Also from this century is the font, in Purbeck marble; it is octagonal and on a stem and base. Around 1600 the stone spire on the tower was taken down and a wooden replacement built.
Generations of villagers worshipping there saw little change in their church until the restoration of 1866-7. The spire and part of the tower collapsed in 1866 during the renovation and a new shingled spire was built. It was contructed on the ground and raised to the top of the tower by cables attached to steam engines stationed on the adjoining hillsides. The shingles were originally of oak but these have been replaced by cedar ones. Numbers attending declined during the 20th century and by 1976 there were only seven regular members of the congregation. The church closed and was declared redundant; it was taken over by the Redundant Churches Fund in 1978 and they have maintained this interesting church since then. There are four bells of 1661, 1663, 1731, and 1882. The parish registers from 1577 are held in the Wiltshire and Swindon Record Office.