The Reformed Political Party (SGP) is a conservative Reformed Christian political party in the Netherlands, notable as the oldest existing party in its current form, having consistently operated in opposition since its inception in 1918. Founded by orthodox Protestants led by pastor Gerrit Hendrik Kersten, the SGP initially focused on opposing perceived "state coercion" such as compulsory vaccination and insurance laws.
Despite failing to win a seat in its first election, the party gained its first parliamentary representative in 1922 with Kersten. A significant moment occurred in 1925 during the "Night of Kersten," when the SGP's successful opposition to funding the diplomatic mission to the Holy See led to the fall of a cabinet, boosting their public profile and seat count.
Throughout its history, the SGP has maintained a stable presence, consistently securing between 1.5% and 2.5% of votes in general elections. Even after Kersten was barred from parliament post-WWII due to his wartime stances, the party continued under leaders like Pieter Zandt and Cor van Dis sr., establishing itself as a "testimonial party" that consistently represents its orthodox Christian ideals in Dutch politics.