God commands genocide, my challenge to Claude Mariottini

There's this book called Show Them No Mercy (Grand Rapids: Zondervan, 2003) wherein several Christian scholars debate the thorny issue of the bible-god's apparent ordering the ancient Hebrews to slaughter all Canaanite men, women and children living in certain specified locales, and whether this can be reconciled with God's alleged command in the NT that his people be loving toward everybody else.

In other words, a problem of consistency that only worries those who ascribe to bible "inerrancy".

One of the Christian scholars to contribute an article in that book was C. S. Cowles, who wrote the article “The Case for Radical Discontinuity". He emphasizes NT passages which say the Old Covenant was imperfect and is passing away.

Dr. Mariottini has a blog and responded to Cowles, trying to argue under a presumption of biblical inerrancy that there is no inconsistency between the OT God commanding such genocide and the NT God who commands people to love one another.

I replied to Mariottini, see here.  I post the content below in case the good doctor deletes my post:

          Barry Jones says:
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June 17, 2020 at 4:25 pm

Dear Dr. Mariottini, 

Frank Turek and other "apologists" strongly emphasize that objective morality proves god. Turek thus argues that most of humanity recognize rape as immoral, yet atheism cannot account for this pattern of opinion in human history, therefore, god did it. But most people also strongly oppose infanticide (Numbers 31:17, 1st Samuel 15:2-3), and they equally oppose using fire to kill a preteen girl merely for having premarital sex in her father's house (Leviticus 21:9, by having sex in her father's house, she likely still lives there, and thus is likely still unmarried and thus likely not older than about 12). 

If the collective human condemnation of rape proves God, why shouldn't we extend Turek's logic and similarly presume that because it is the Holy Spirit who convinces everybody that rape is absolutely immoral, it is also the Holy Spirit who convinces everybody that infanticide and burning children to death are absolutely immoral?

By what criteria do we decide when collective human moral opinion ultimately stems from the Holy Spirit, and when it doesn't?

Sure, that would have the effect of proving those parts of the bible are not inspired by God, but wouldn't logical consistency be a higher priority than bible inerrancy, given the former is beyond question, while the latter is the subject of endless confusion and disagreement within the Evangelical Christian camp?

Or do you think Turk is merely overstating the force of the moral argument for God?