Well, first is the testimony that the Scripture gives about God's direct revelation to particular individuals: Adam, Noah, Abraham, Isaac, Jacob, Moses and the Children of Israel.
Second, is what God says in those Scriptures about who was alive to carry out the preaching of the Word.
We will think about this in round terms of years as the Scriptures describe them. The year numbers given below are close estimates. We will look at them from the terms the Scriptures use with respect to the age of Adam. I'm sure many readers have made their own charts of these chapters in Genesis (5, 11, 21, 25, 35, and 47). I'll include a full table at the bottom with the refrences to the passages. Genesis does not, except in a few cases, record the month or day of month for these events.
Let us list and illustrate these genealogies and consider what it means with respect to who was able to preach the promised redemption from Satan, Sin, and Death promised in Genesis 3.
Adam was 130 years old when he begat Seth. And Adam lived for 930 years.
This means that in the terms of the genealogy of Genesis 5 we can list the year of Adam's life when the following were begotten/born:
|Adam's Age||Descendant born|
These lives all overlapped with Adam's life. Noah was born after Adam's death, the 1056th year of Adam's age. It would have been easy for these men to hear Adam's teaching directly from Adam himself. Because they are direct descendants of Adam, it would be reasonable to assume they were instructed by Adam.
Adam's son, Seth, died in the 1042nd year of that era. Noah could not have known either Adam or Seth.
But all of them except Enoch were living on the earth during the lifetime of Noah. Noah would have had to rely on the teaching of those who heard it directly from Adam.
|Patriarch||Year of Death|
Noah's son Shem was born in 1556, meaning that even Shem had 100 years of life during which he was able to speak to Methuselah and Lamech, who were alive while Adam was still living.
The information in Genesis 5 could be charted like in the following way to demonstrate who was able to speak to whom:
At the bottom of this chart are the years of Adam's age. This chart is colored to demonstrate that in the Biblical text there is only one degree of separation between Noah and Adam--and even for that matter, between Shem and Adam.
Even though Noah had such close ties to Adam through those who knew Adam, God re-established direct contact with Noah.
Then came the Judgment in the Flood.
This next chart is an illustration of those who were living at the same time Noah and Shem were alive after the Flood.
Again, the years at the bottom are the years of Adam's age. The lighter blue area shows that Abraham lived while Noah was still alive. Abraham was born in 1948, Noah died in 2006. That is an overlap of 57 years. Abraham died in 2123. Shem died in 2158. Shem outlived Abraham by about 35 years.
Isaac was born in 2048. This means that Shem was alive for most of Isaac's lifetime.
Jacob was born in 2108. This means that Shem died when Jacob was about 15 years old.
So let us look at degrees of separation. The closest arrangement is two degrees of separation between Jacob and Adam.
Adam --> Methusaleh --> Shem --> Jacob
What this shows is that the text of the Bible insists that Abraham, Isaac, and Jacob lived at the same time as the men who God saved through the Flood. They could hear from Noah and Shem their first-hand experiences with those who knew Adam personally and the Promise God gave to him; those who fell away in that time and the loved ones who were killed in the Flood; and of the renewing of the Promise God gave to Noah.
But God did not leave Abraham, Isaac and Jacob with just the oral report of witnesses.
The text also records that God spoke directly to Adam, Noah, Abraham, Isaac, and Jacob. It records that God made specific covenants with each of them with regard to the Promise of Redemption.
So, even though these men were actually very close to each other, God still left nothing to just oral transmission. He Himself proclaimed the Promise to each generation down to the time of Jacob and his sons went into Egypt. And He Himself proclaimed the Promise again when He brought the Israelites out by the hand of Moses.
Then God also put His Promise into writing, which we still have from Moses, the Prophets, the Evangelists and the Apostles to this day.
Here is a fuller table with the data and the Bible references:
|Patriarch||Year Made/ Conceived||X years old when he conceived the next||Lived Z years after||Age at Death||Year Died from Adam's Age||References||Age at Flood||Departed Haran||Ref|
|Noah||1056||500||950||2006||Gn 5:32; 7:11; 9:29||600|
|Abram||1948||100||175||2123||Gn 21:5; 25:7||75||Gn 12:4|
|Isaac||2048||60||180||2228||Gn 25:26; 35:27-29|