It is a three-nave longhouse with a raised central nave and a flat wooden ceiling. The masonry is made of naturally treated light rubble stone. The 33.5-meter-long central nave is separated from the side aisles by rectangular arcades.
The church building leans asymmetrically against the 50-meter-high tower, the lower part of which is the oldest part of the structure. Under Pastor Joseph Kempf (1887-1913), the tower was raised because the new building covered part of the sound holes and affected the ringing effect. As a result, the inserted "floor" is significantly above the roof ridge of the longhouse and now serves as a "bell chamber."
The right aisle has two entrances: the south portal and the entrance to the Mother of God Chapel. The south portal – originally the main portal – is bordered on both sides by a column with a cube capital, which continues into wall projections in the portal arch. Between the arch tension and the door lintel is a tympanum (Greek: drum), which is equipped with a flat relief of an "encircled" cross. The west exit, which is today considered the main portal, is rather unadorned and was originally meant to be just a "small door."
The entrance to the "Mother of God Chapel" is framed by two columns with leaf capitals. Above the arch tension is a niche in the wall housing a statue of Mary from the 19th century. On the southern outer wall of the tower is a stone cross, created in the second half of the 17th century under Pastor Jacob Spang (1668-1689). In World War II, this corpus was damaged by an artillery shell. Pastor Sylvester Hainz (1960-1981) had the valuable corpus of red sandstone restored and reattached to the cross.
There is also a "crypt," as the sloping terrain on the eastern part of the church was not to be filled with sand. Thus, this "crypt" is not an underground facility. It is now a storage and heating room and is only accessible from the outside.
In the church, near the west entrance, stands the massive baptismal font from the old church, which had long been lost until it was discovered in a yard where it was used as a trough. The number 1492 is engraved on one side, presumably the year of its creation. It belongs to the "lion baptismal fonts," whose base is formed by four reclining lions that unfortunately are no longer present. The baptismal font now serves as a holy water basin.
On the western rear wall is a "Crucifixion group." However, the cross is not "framed," as usual, by Mary and John, but by the two church patrons St. Martin and St. George. Both statues, carved from wood around 1700, adorned the old church. The cross originates from Flonheim, the corpus from Mittelheim/Rheingau.
Figures of saints are placed on the walls of both side aisles. Most were not specifically created for the parish church but were "collected" over time.
The most important figures are St. Boniface, St. Anthony of Padua, St. John the Baptist, St. Francis of Assisi, St. Roch, St. Wendelinus, St. Aloysius, and St. Sebastian. The figure of St. Christopher, attached to a column, comes from Merano (Tyrol).
In the middle of the left aisle stands the baptismal font that has already been used in the old church. The cover is adorned with a figurative representation of the baptism of Jesus in the Jordan by John.
At the end of the left aisle stands the crucifix altar from 1906. The reliefs of the altar structure depict the "finding of the cross" and the "elevation of the cross." The cross that towers over the altar was created around 1700 and was taken from the old church.
In the chancel of the church, a new "celebration altar" made of natural sandstone stands at the front, along with a similarly designed ambo. A special feature is the arrangement of the "reliquary grave," which is not – as usual – integrated into the altar slab. The relics are visible behind glass on the front side of the base.
In the apse stands the high altar from the year 1900. Beneath the altar table made of red sandstone are five reliefs made of white Courson. All relate to the Eucharist, which is stored in the tabernacle of this altar. The altar structure depicts the wedding at Cana and the Last Supper. The concha in the apse of the main nave is painted with an image of Christ enthroned among saints connected to Germany, the Diocese of Mainz, or the parish community. Also recognizable is the Finthen virgin Agnes Pfeifer, who was murdered in 1754 while defending her innocence (Easter eggs). She does not have a halo.
On the right wall in the chancel is the "Madonna of the Cloak," a 1.10-meter-high late Gothic sculpture made of lime wood. It came to Finthen under Pastor Autsch and is a significant work of art: Mary carries the infant Jesus in her arms. Angels hold her wide cloak outspread. Many people of all stations are sheltered underneath.
The "choir" of the right aisle has been considered the "Mother of God Chapel" from the very beginning. It was redesigned in 2003 and separated from the rest of the church space by a grille. On the end wall is the Marian altar from 1892. The side wings of the altar structure, rebuilt in 1935, are decorated with carved reliefs. They depict scenes from the life of Mary. Above the tabernacle stands a baroque statue of Mary from the old church. The Mother of God Chapel contains the graves of the virgin Agnes Pfeifer and Pastor Joseph Kempf. A separate entrance provides access to the "chapel" during the day.
Noteworthy are also the twelve (!) Stations of the Cross from 1965. The congregational singing is accompanied by an organ built in 1853 by B. Dreymann. Unfortunately, it is no longer in its original form. Only a few registers trace back to Dreymann.
The ringing of the church consists of five bells: 1. Philip's bell (cast in 1895 - 2090 kg), 2. Mary's bell (1895 - 1060 kg), 3. Joseph's bell (1956 - 850 kg), 4. Martin's bell (1897 - 450 kg), 5. Bernard's bell (since 2004 - 382 kg).
