If one has the person responsible for cow killings in front on him and the person will not listen to one's message i.e. is a demoniac human due to his circumstances of religion or ideology; then is it not a good thing to kill the person instead of letting him incur bad karmas?

This question has been answered by His Grace Gokula Candra Prabhu, a senior disciple of His Holiness Bhakti Vikasa Maharaj upon Maharaj's request.