Why would God tempt Abraham to do something detestable just to prove his faith? This is not typical for the sort of character Christians think of God as having. And if it is, that might explain why so many Christians here scare me in their ability to hurt other people, "because God says so".
Tests of trust are typically the sort of thing that mobsters, thugs, and abusive spouses do.
I've thought on that a couple of times, trying to plumb the mystery, and it seems to me somehow connected to the fact that child sacrifice is perhaps the greatest of all evils --
Bible Gateway passage: Deuteronomy 12:29-31 - New International Version.
But it's everywhere, at that time, it's likely. The norm, like slavery also -- all the world has it going on. It's not a thing that can be tolerated too long, but eventually would justify total destruction --
Bible Gateway passage: Malachi 4 - New International Version
When the Canaanite cities that had been sacrificing children in fires were to be destroyed, God could of course have done it in any manner, such as He did to Sodom and her sister cities for their high levels of notable evils, including abominations like arrogance/haughtiness, and the deep evil of all lack of charity:
Bible Gateway passage: Ezekiel 16:49-50 - New International Version
Why did He have Israel personally destroy the Canaanite cities (or participate) when He could have done it without them? (sending all on to the Day of Judgement, where the innocent and the forgiven would be separated from the guilty (perhaps also the gospel was offered to even these dead? 1 Peter chapter 3?)).
Perhaps Israel was made to see the destruction first hand, often by their own hands, so that they would have impressed on them the lesson of
Bible Gateway passage: Deuteronomy 12:29-31 - New International Version. Witnessing right in front of their eyes the in-time outcome of child sacrifice, so that they would be very much learning deeply how wrong this near-universal thing was, and not take it up.
Perhaps that did work for a time. We know eventually Israel did anyway, and that led to the later devastation and the captivities.
Notice this dialog though about the question of what if some people are righteous in the city doing the many of the worst evils --
Genesis 18 NIV Would God spare the city if it had 10 righteous in it?
Lot espcapes, as does later in Israel a remnant, those not participating in the great evils. We all are under the condition that we might be able to be among the "few" that find the narrow gate, Christ said, that leads to Life.