(B-Chan) 1. In a Christian monarchy, where Church and State are bound together, heresy against the Church is treason against the State. Therefore, in such a situation, heretics are traitors, and traitors deserve death.
Just how do you propose to kill those "heretics" when your "Christian (read Catholic) Monarchy is in power?
However, so does everybody else. “Let he who is without sin cast the first stone.” Therefore, the State should be extremely cautious about how it administers capital punishment.
The Catholic Church teaches that the death sentence should not be imposed except when no other options exist to safeguard society from the criminal under sentence. In a Christian Monarchy, the justice meted out by the courts would undoubtedly follow this standard. Modern jurisprudence has access to facilities and techiques that were unknown or unavailable in medieval times; I suspect that in most cases at law in a hypothetical Christian government, Christian mercy would prevail, resulting in imprisonment for most crimes, and reserving the stake and/or noose for those whose crimes truly merited the ultimate punishment.
That being said, I repeat: traitors deserve death, and in a society based upon Christianity, heretics may be rightly counted as traitors, as they seek the overthrow of the existing social order. The death penalty itself is an entirely Scriptural and moral practice in such cases, presuming of course that due process is observed.
It's obvious that you are unfamiliar with the history of Europe. Before posting, please do yourself a favor and educate yourself on the true nature of the various Inquisitions and how they operated. (Note: Books by Chick Publications are wholly fantastic and are not acceptable as historical texts.) Interested parties may find this link to be instructive.