Genesis 6:2-3: “God spoke to Moses and said to him, ‘I am the LORD. I appeared to Abraham, to Isaac, and to Jacob, as God Almighty, but by my name the LORD I did not make myself known to them.'”
Though the LORD (YHWH) is God’s covenant name, but it relates also to deliverance. Here the LORD, God Almighty, reveals himself to Moses as the LORD, and adds a strange caveat: that Abraham, Isaac, and Jacob were not given the privilege. But throughout Genesis it says that the LORD appeared to so-and-so, and that so-and-so called upon the name of the LORD. Joshua, who was probably alive at this point, was named as “the LORD is salvation.”
So what’s the deal, here then? Did the LORD forget the way he revealed himself to Abraham? What does the LORD mean here?
Clearly it does not mean that the LORD’s name as “the LORD” was unknown. Abraham knew that God Almighty is the LORD, and the people of Israel knew their God was the LORD. What it does mean is that the LORD’s manifests himself and his “name” (related to his character, who he is and by extension what he does) to Moses and Israel in a way that Abraham and his more immediate sons had not seen.
They had not seen redemption; at least, not like Moses and that generation would. The LORD remembers his covenant (Ex 3:5) with the Abraham, Isaac, and Jacob when he redeems his people through Moses. Abraham had seen God make a covenant–but to remember that covenant, to redeem his covenant people–Abraham had not seen that. Not like Moses did.
And neither had Moses seen what we now have seen of the LORD’s redemption and remembering.