Christians,if God commanded you shall not kill,how do you feel about the inquisition?

They burned people alive just because the heretic God was different by the inquisition God.So how do you feel about them?Did they had God permission or was it a continuum to the Roman legacy,for the romans in the times of Nero persecuted Christians,they might have done so so that the Romans can live on through the inquisition?Thank you!