The building is said to have been constructed during the Carolingian rule and to be the first Christian settlement in Holstein. According to the Society for Schleswig-Holstein History, however, it is disputed whether remains of walls from the Carolingian period can actually be found on the church. Today's building was built after the Thirty Years' War.
In 1932 an archaeological investigation was carried out by Alfred Kamphausen and in 1980 an excavation was carried out by the Archaeological State Office of Schleswig-Holstein under the leadership of Dr. Willie Kramer. This research team came to the conclusion that the Schenefeld Bonifatiuskirche cannot be regarded with certainty as one of the early medieval baptisteries in northern Albingia.
During the excavations it was found that after a fire in 1628 the round tower was demolished and a square tower was built in its place. However, the foundation did not hold up, so the tower was demolished again in 1732 and replaced by a lighter one with a turret.
Memorial stones and grave crosses in the older part of the cemetery, which is no longer in use, directly by the church, bear witness to very old graves.
Source: de.wikipedia.org/wiki/Bonifatiuskirche_(Schenefeld)