Local legends maintain that the evangelization of Châlons by St. Memmius, sent thither by St. Peter and assisted by his sister Poma, also by St. Donatian and St. Domitian, took place in the first century.

Louis Duchesne, a prominent scholar of early Christianity in Gaul, assigns the founding of the See of Châlons to the fourth century.

[9] The new Cathedral of S. Étienne was consecrated in 1147 by the exiled Pope Eugene III, assisted by eighteen cardinals, with Bernard of Clairvaux in attendance.

[10] In 1253, when he was visiting Rome, Bishop Pierre de Hans was able to obtain what was claimed to be a fragment of the head of S. Étienne (Stephen the Protomartyr) from the Abbot of the monastery at S. Paolo fuori le mura.

The Jesuits directed the school until they were expelled from France in 1762, at which point the collège was turned over to laymen and secular clergy until the end of the monarchy in 1791.

The bishop appointed the four Archdeacons and the Treasurer, while the Dean, the Cantor, and the Succentor were elected by the Chapter of the Cathedral.

[22] Nôtre-Dame de l'Epine, near Châlons, was a place of pilgrimage as early as the beginning of the fifteenth century, thanks to the mysterious discovery of a miraculous image of the Virgin Mary.

[23] In 1790 the National Constituent Assembly decided to bring the French church under the control of the State.

Civil government of the provinces was to be reorganized into new units called 'départements', originally intended to be 83 or 84 in number.

Since there were more than 130 bishoprics at the time of the Revolution, more than fifty dioceses needed to be suppressed and their territories consolidated.

The Bishops of Reims, Châlons, Soissons and Troyes protested, addressing letters to their clergy and to the 'electors' and warning them to take no account of the activities of the government as regards the Church.

Then, on 15 March, they elected Nicolas Diot as Bishop and Metropolitan of Marne, and he thus acquired control over the suppressed diocese of Châlons-sur-Marne.

[28] In the meantime First Consul Napoleon Bonaparte was preparing to end the religious confusion in France by entering into a Concordat with the Vatican.

On 29 November 1801, by the bull Qui Christi Domini, Pope Pius VII suppressed all of the Roman Catholic dioceses in France, and reinstituted them under papal authority.

The Concordat of 1801 was unilaterally abrogated by the Law of Separation of Church and State, enacted on 9 December 1905.