Abraham "offered" Isaac to the mighty one (elohim) because he was still acting under a basic ancient pagan or heathen culture. This was a culture that believed that a great gift, such as one's only child late in life, or any great blessing deserved thanks to one's mighty one (elohim). The pagans thought that even greater blessings would result. This as we know is a completely false concept.
YHWH corrected Abraham by having His messenger call out to Abraham to prevent this act of heathen intent and instead provide a substitute so Abraham would not have to gift Isaac but still be able to bring a gift to YHWH in the form of a pagan burnt offering.
"Now it came to pass after these things that God tested Abraham, and said to him, "Abraham!" And he said, "Here I am." Then He said, "Take now your son, your only son Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt offering on one of the mountains of which I shall tell you."" (Genesis 22:1-2).
Though you live about 4,000 years after the event you claim that what the Bible has recorded is completely backwards from what you believe the event to be. God, in His inspired Word, states that He asked Abraham to offer Isaac as a burnt offering. You claim that it was Abraham's idea and it was prompted from Abraham's pagan beliefs. Yet the Bible is clear that Abraham was not a pagan but a believer in the Almighty God.
"For it is written: "I will destroy the wisdom of the wise, And bring to nothing the understanding of the prudent." Where is the wise? Where is the scribe? Where is the disputer of this age? Has not God made foolish the wisdom of this world?" (I Corinthians 1:19-20).
"Indeed, let God be true but every man a liar. As it is written: "That You may be justified in Your words, and may overcome when You are judged" (Romans 3:4).