The concordat was solemnly promulgated on Easter Day 1802, but the government had added to it unilateral provisions of Gallican tendencies, which were known as the Organic Articles.
In 1718 he entered into a correspondence with William Wake, archbishop of Canterbury, with a view to a union of the English and Gallican churches; being suspected of projecting a change in the dogmas of the church, his papers were seized in February 1719, but nothing incriminating was found.
The following year, the question of the intervention of kings in the election of bishops having been raised in a pamphlet by Charles Hersent (Optatus Gallus de cavendo schismate, 1640), Marca defended what were then called the liberties of the Gallican Church, in his celebrated treatise De concordia sacerdotii et imperii, seu de libertatibus ecclesiae gallicanae (1641).
His principal works (1 579, 1 599) treat of Gaulish and French antiquities, of the dignities and magistrates of France, of the origin of the French language and poetry, of the liberties of the Gallican church, &c. A collected edition was published in 1610.
The confessors of the Gallican Church at Lyons were of opinion that communion ought to be maintained with the zealots of Asia and Phrygia; and they addressed a letter to this effect to the Roman bishop, Eleutherus.