Saxons were fighting back against their conversion.
Step-by-step explanation:
The Saxons who were made to forcefully change their religions, did not want to peacefully accept the change of religion. They fought back against this forceful conversion and this they did by attacking the churches and the officials of the church.
But then certain laws were enacted by Charlemagne which prohibited these attacks on the churches or on the officials of the church and punished those people to death who did not follow these laws and deviated from these laws.