This doctoral thesis aims to shed light on the process of Evangelization and Christianization of the middle Meuse basin between the beginning of the 4th century and the beginning of the 9th century, through a reinterpretation of written sources and a mobilization of increasingly abundant material sources. Four main hypotheses are put forth, starting with the continuous nature of this process, which did not experience a sudden halt during the 5th century, a period supposedly marked by darkness for Christianity due to the destructive nature of the barbarian invasions. According to this pessimistic vision, these invasions were allegedly so detrimental that the resumption of the process of spreading and anchoring Christianity in the 6th-7th centuries would not have been possible without the intervention of foreign missionaries, mainly from Aquitaine and Ireland. The second point defended in this thesis will be to prove that, on the contrary, Christianization was an essentially endogenous process, led both by the episcopate and by the lay aristocracy. These joint efforts contributed to the birth of a Christian society in the 6th-7th centuries, a society in which paganism no longer had its place but whose degree of Christianization remained subject to improvement. This is the third point, that of Christianization in depth. Lastly, the fourth achievement of this research is that of writing and rewriting of the phenomenon of Evangelization and Christianization, which notably saw the emergence of the topos of the fight against paganism, a topos that intensified over the centuries.