Geert was a farmer and lay-preacher ("oefenaar") in the time of the so-called "Secession." He was one of the first in the area to leave the Reformed (Hervormde) Church because he thought it was becoming too liberal. At first, the family would attend morning services at the Reformed Church, but then attend group meetings in the afternoon or evening. However, these meetings, held in homes and barns, were illegal, and could be punished by fines and imprisonment. Geert became a much-loved lay-preacher in these meetings.

Finally, this group of "seceders" drew up a document stating their intentions to withdraw from the State Church and establish a church of their own; Geert was one of four men to sign this first document. On 24 June 1844, a group of eight men, who now called themselves Altreformierten (Old Reformed), assembled for their first Synod, Geert among them. In 1848, these and other seceders won the freedom to form their own churches. (By that time, many people had already left for America, where their churches would be known as Christian Reformed.)

Geert experienced much persecution, and at one point was imprisoned in the dungeon of the old Castle of Bentheim with the well-known Rev. J.B. Sundag (Sondag?). After being freed, he was chosen as elder until death.

Agneta apparently died from drowning.