You said: "...the Lord made sure the church had such power until it didn't need it any more." "...so heresy and heretics were within their rights to execute the laws in place until nations began the separation of jurisdictions like England did in King James' day."
I think the Catholic Church gave itself the power to "execute the laws in place". The Church of God is under the New Covenant, and as far as I can tell, is under no command to torture and kill people.
Rom 13:1 Let every soul be subject unto the higher powers. For there is no power but of God: the powers that be are ordained of God. 2 Whosoever therefore resisteth the power, resisteth the ordinance of God: and they that resist shall receive to themselves damnation. 3 For rulers are not a terror to good works, but to the evil. Wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same: 4 For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to
execute wrath upon him that doeth evil. 5 Wherefore
ye must needs be subject, not only for wrath, but also for conscience sake. 6 For this cause pay ye tribute also: for they are God's ministers, attending continually upon this very thing. 7 Render therefore to all their dues: tribute to whom tribute
is due; custom to whom custom; fear to whom fear; honour to whom honour.
hence no one gets power without God's approval. and the if you notice when the enemy of God's people Israel get power over them its usually because the Lord had reason for it. also note that the text is written by a man who was ordained by God and persecuted by Jews and Rome. so accusing those with power to be cruel is pointless man is cruel and ruthless no matter what he does because that is the nature of man. if you had no influence of the Lord in your life you'd be the same. without the Lord we are all animals by nature.
so any power in the world is given and or granted by God.
anyway, when there is a vacuum of power in the world just like a wild dog pack the next most powerful takes the reign. which is simply what happened in the case of Rome's dwindling of power. so criminal and civil prosecution was something they administered.