It seems to me that you have touched on a somewhat controversial subject, though not particularly for Jews who understand the story from all its angles. I will provide the Jewish perspective on the matter.
First, we must understand that the story of Isaac's sacrifice is not a simple matter to understand. We, as humans, particularly in the modern age, find it difficult to comprehend something as controversial as sacrificing one's son.
In Judaism, there are two ways to interpret this story. One interpretation is the standard one as understood by the vast majority of bible scholars and bible readers. The other interpretation is much more complex and much more controversial. Both lead to the same conclusion, but both take two completely different paths.
Let's begin with the standard interpretation:
Isaac was a grown man (somewhere between 25 to 37, depending on the source) and could've easily fought off his father if he wished not to be sacrificed. Yet Isaac did not resist and did not make a sound. Like a righteous man, he has accepted his fate. G_d instructs Abraham to sacrifice his son without giving him a reason for it. The practical explanation suggests that it was the most heavenly, most difficult, most powerful test ever given to a man to test his belief in G_d. The story goes on that just before Abraham was to sacrifice Isaac, an angel interferes and manifests a ram (or a goat, depending on the source) where Abraham chooses to spare his son and sacrifice the ram instead.
The second interpretation is not widely accepted, but one that was suggested by several Jewish scholars of old. Keep in mind that this is the unorthodox interpretation and by far the most controversial of the two:
The story starts the same. The only difference is that the angel is too late to stop Abraham from sacrificing his son and Isaac is in effect, sacrificed and has died. Further interpretation suggests that when Abraham has sacrificed his son, many angels cried and screamed in agony to G_d as to why He would allow such a cruel, unmerciful act. It is further explained that G_d resurrects Isaac from the dead by bringing him into His "Raqia Shevi'i" (loosely translates to "Seventh Heaven") and reinstalling, so to speak, Isaac's soul and then bringing him back to life.
As you can see, both interpretations take different paths, but both lead to the same conclusion - Isaac lived. Whether he wasn't sacrificed and lived or whether he was sacrificed and resurrected, the result is the same. This clearly suggests that G_d never intended for Abraham to kill Isaac, but rather sacrifice or attempt to sacrifice Isaac in order to test Abraham's trust in Him.
Some suggest that G_d was indeed testing Abraham's faith in him, though I believe it goes considerably deeper than that, into areas and ideas we may never comprehend. Someone here used the term "obedience" which is grossly incorrect in this case as G_d did not demand obedience from Abraham, but rather inquired into his belief in Him. So, in effect, this was much more a test of trust and free will rather than a test of obedience. Obedience relates more to a command. G_d has not "commanded" Abraham to sacrifice Isaac. G_d has "asked" Abraham to sacrifice Isaac. Because it was such a grueling test of free will and Abraham has stepped to the "challenge", G_d has since considered Abraham as his own son and has promised his offspring and his people great lands and wealth.
I could discuss this much further as there are other implications to consider such as the rather large gap between the time of Isaac's sacrifice (when he was around 30 years old, depending on the source) to the time Isaac married Rebekah (when Isaac was around 40-45 years old). There are of course other implications, but I would not venture to discuss them at this point as I have to call it a night.
Yes, I meant to add one of your points earlier. I have taught Genesis and Exodus to mixed classes of Jews, Christians, and at least some students who have never even seen a Bible.
In western art, Isaac is usually portrayed as a young man, maybe a teenager. But some of my Jewish students who have studied the Hebrew Bible said that the traditional Jewish interpretation of this passage is that Isaac was in his 30s, old enough to be responsible, and old enough to fight off his father if he had chosen to. Abraham was more than a hundred years old when Sarah CONCEIVED Isaac, so presumably he was over 130 at the time of the sacrifice.
In other words, it must be concluded that Isaac was not forcefully tied up and placed on the burning pile to have his throat cut, but that he CHOSE to permit his father to do this. In other words, he was tested too, and he too chose virtuous obedience.
Interestingly, in Buchanan's 16th-century Latin tragedy about Jephtha's daughter, he makes the same presumption: that she voluntarily agreed to be a sacrifice so her father could fulfill his unfortunate promise. This doesn't make these stories a whole lot easier, but it does put another light on them.