Yes it does matter…
Servetus was murdered on 10/271553.
Calvin wrote the following after the murder in early 1554 in defense of his role in the murder:
“Whoever shall now contend that it is unjust to put heretics and blasphemers to death will knowingly and willingly incur their very guilt. This is not laid down on human authority; it is God who speaks and prescribes a perpetual rule for his Church. It is not in vain that he banishes all those human affections which soften our hearts; that he commands paternal love and all the benevolent feelings between brothers, relations, and friends to cease; in a word, that he almost deprives men of their nature in order that nothing may hinder their holy zeal. Why is so implacable a severity exacted but that we may know that God is defrauded of his honour, unless the piety that is due to him be preferred to all human duties, and that when his glory is to be asserted, humanity must be almost obliterated from our memories? Many people have accused me of such ferocious cruelty that I would like to kill again the man I have destroyed. Not only am I indifferent to their comments, but I rejoice in the fact that they spit in my face.”
Prior to the murder he wrote things which demonstrated that he premeditated his direct role in the intentional murder of Servetus.
To claim that God justified this murder is justified by the Old Testament and more pointedly the Mosaic Law as John Calvin tried to do is blatantly in error and goes against what Jesus said for us today.
Ye have heard that it was said by them of old time, Thou shalt not kill; and whosoever shall kill shall be in danger of the judgment:  But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire.  Therefore if thou bring thy gift to the altar, and there rememberest that thy brother hath ought against thee;  Leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift.  Agree with thine adversary quickly, whiles thou art in the way with him; lest at any time the adversary deliver thee to the judge, and the judge deliver thee to the officer, and thou be cast into prison.  Verily I say unto thee, Thou shalt by no means come out thence, till thou hast paid the uttermost farthing. Matthew 5:21-26
God would rather none to perish but for all to come to repentance. If Servetus was a heretic then to murder him leaves no future room for him to repent. No amount of claims regarding unconditional election can justify this murder because if you do not allow the time in one’s life to carry on you never know if they will repent or not. This goes against God’s desires for us and how we should treat our enemies but more importantly how we treat His enemies in the times we live in today.
Here are some of Calvin’s quotes that demonstrate it was premeditated murder on his part:
“God makes plain that the false prophet is to be stoned without mercy. We are to crush beneath our heel all affections of nature when his honor is involved” 1951
“[They] well deserve to be repressed by the sword which is committed to you, seeing that they attack not the King only, but God who has seated him upon the throne, and has entrusted to you the protection as well of His person as of His majesty.” 1548
“But when I perceived that the fury of certain bad men had risen to such a height in your realm, that there was no place in it for sound doctrine, I thought it might be of service if I were in the same work both to give instruction to my countrymen, and also lay before your Majesty a Confession, from which you may learn what the doctrine is that so inflames the rage of those madmen who are this day, with fire and sword, troubling your kingdom. For I fear not to declare, that what I have here given may be regarded as a summary of the very doctrine which, they vociferate, ought to be punished with confiscation, exile, imprisonment, and flames, as well as exterminated by land and sea. This, I allow, is a fearful punishment which God sends on the earth; but if the wickedness of men so deserves, why do we strive to oppose the just vengeance of God?” 1536.
I have yet to see a quote from Calvin where he confessed and repented of his role in Servetus’ murder.
Why am I constantly bringing this up? To try to wake up any of Calvin’s followers today who will listen to reason. I hope to help show them where their doctrines originated from, a very hate filled murderous man who justifies everything on God’s decrees instead of actually taking ownership of his own heinous sins as well as repenting of them.
It does matter that a man who is essentially venerated as a Church Father died an unrepentant murderer and it does matter whether anyone chooses to follow after the teachings of such a man.