Louis has made attempts to convert his pagan or "schismatic" subjects to Catholicism even by force.

The conversion of the pagan Cumans who had settled in Hungary a century before is completed during his reign, according to John of Küküllő.

After the conquest of Vidin, he had sent Franciscan friars to the new banate to convert the local Orthodox population, which has caused widespread discontent among the Bulgarians.

In 1366, he had ordered that all Serbian priests be converted and rebaptized.

He has also decreed that only Roman Catholic noblemen and knezes sre allowed to hold landed property in the district of Sebes in Temes County.

Louis supports the religious orders, especially the Franciscans and the Paulines, for whom he and his mother have set up dozens of new monasteries.

Upon Louis's request, Pope Urban V sanctions the establishment of a university in Pécs in 1367, with the exception of a faculty of theology.

However, Louis does not arrange for sufficient revenues and the university will be closed by 1390.