NOTES for Joh 8:39-40
Jews have always considered themselves children, descendants, of Abraham, and this is an undoubted historical fact. This fact was enough for every Jew in every age to consider himself belonging to the people of God. But then the Messiah comes and poses the question differently.
It turns out that it is not enough to be a descendant of Abraham by blood; one must also be his successor in spirit. And that is more difficult. Indeed, what did Abraham do? He followed God, who called him. But what did this mean for him? Abraham knew nothing about the God who called him; for him the God of Israel was still an unknown God. Abraham came to know Him already on the road to Palestine and later in Palestine itself. At the beginning, he simply had to entrust himself to the One he did not know. To believe at the first encounter. Abraham, of course, heard God's voice, but in those days hearing the voice of some god or spirit was not so rare.
There were many gods and spirits, and many voices as well; whom to trust was for each person to decide. The voice that called Abraham after itself was the voice of the Unknown. This voice promised much, but could it be trusted? Abraham believed. His heart told him that the Unknown One was not deceiving him. And in this he is the complete opposite of those deeply religious but very distrustful Pharisees who constantly demanded proofs of Jesus' messiahship, and proofs that matched their own ideas about the Messiah.
If Abraham had been like that, there would have been no Jewish people, simply because such an Abraham would never have believed the unknown God. And of course, with the openness that characterized Abraham, he would never have begun to persecute, much less try to kill, a person attempting to tell him something new about his God. This is what distinguishes Abraham from those who turned out to be his descendants by blood but not by spirit. Abraham had every possibility of entering the Kingdom. His descendants, however, had serious problems with this. Not all of them, of course, but many. Especially those who considered themselves completely ready both to meet the Messiah and for the Kingdom.