What social and religious factors are given to account for the harsh response to witchcraft?

At that time, Christianity was very clear on the sins of trusting 'other gods' Beside Jesus Christs

Witchcraft at that time was regarded as the embodiment this very sins. Since at that time the christians church had a massive influence within the government body, they could made a societal regulation that demonize witchcraft, and many of them were executed as the result.