The Confession of Faith, popularly known as the Belgic Confession, is a doctrinal standard document to which many of the Reformed churches subscribe. The Confession forms part of the Three Forms of Unity of the Reformed Church, which are still the official subordinate standards of the Dutch Reformed Church. The confession's chief author was Guido de Brès, a preacher of the Reformed churches of the Netherlands, who died a martyr to the faith in 1567, during the Dutch Reformation. De Brès first wrote the Belgic Confession in 1559.