According to innocent iii, what actions were french authorities to take against heretics? what reason did he give for taking these actions?

Pope Innocent III (in office 1198-1216) called on church authorities to use excommunication as a tool of spiritual discipline, and called on French nobles to use confiscation of property and banishment as a crusade against the heretics of the Albigensian and Waldensian movements.  

Innocent's stated reason was that these heretics were "traitors to the faith of Jesus Christ," and that even worse than going against sovereign earthly authorities was how the heretics were offending divine majesty.

From the point of view of the "heretics," the strong-arm tactics of the Roman church were in opposition to the faith of Jesus Christ and went against God's desires.