What internal evidence supports the historicity of Abraham?

Question

Is there any internal or small external evidence of Abraham's existence? I have heard a claim from skeptics that Abraham is just flat out invented figure who never existed and even COULDN'T have existed.

Not only has archaeology not proven a single event of the patriarchal traditions to be historical, it has not shown any of the traditions to be likely. - Thomas L. Thompson, The Historicity of the Patriarchal Narratives: The Quest for the Historical Abraham (BZAW 133, De Gruyter, Berlin and New York, 1974), page 328

Is this valid? Note that I am not asking for extra-biblical mentions of Abraham. I am realistic, he was unimportant nomad in illiterate world. However, I am asking, is there any evidence for events and places and customs described in Genesis? Is there any internal evidence in the text itself like criteria of embarrassment or something that must be historical? I have always seen Abraham's life as too simple and non-embellished and non-fantastical for him to be made up. Beyond that, I never saw any other evidence for his historicity.

Answer 1

With regard to evidence for events and places and customs described in Genesis, I found two articles that shed light on the journey of Abram and his family clan, Terah. Thousands of tablets have been found in the ruined palace at Mari confirming the places and peoples mentioned in the Genesis account. Below are brief extracts from the two articles, along with the links so you can read them in their entirety:

The saga of Abraham unfolds between two landmarks, the exodus from “Ur of the Chaldeans” (Ur Kasdim) of the family, or clan, of Terah and “the purchase of” (or “the burials in”) the cave of Machpelah. Tradition seems particularly firm on this point. The Hebrew text, in fact, locates the departure specifically at Ur Kasdim, the Kasdim being none other than the Kaldu of the cuneiform texts at Mari. It is manifestly a migration of which one tribe is the centre. The leader of the movement is designated by name: Terah, who “takes them out” from Ur, Abram his son, Lot the son of Haran, another son of Terah, and their wives, the best known being Sarai, the wife of Abram. The existence of another son of Terah, Nahor, who appears later, is noted.

Most scholars agree that Ur Kasdim was the Sumerian city of Ur, today Tall al-Muqayyar (or Mughair), about 200 miles (300 km) southeast of Baghdad in lower Mesopotamia, which was excavated from 1922 to 1934. It is certain that the cradle of the ancestors was the seat of a vigorous polytheism whose memory had not been lost and whose uncontested master in Ur was Nanna (or Sin), the Sumero-Akkadian moon god. “They served other gods,” Joshua, Moses’ successor, recalled, speaking to their descendants at Shechem.

Abraham had not yet come to the end of his journey. Between Shechem and Bethel he had gone about 31 miles (50 km). It was about as far again from Bethel to Hebron, or more precisely to the oaks of Mamre, “which are at Hebron” (according to the Genesis account). The location of Mamre has been the subject of some indecision. At the present time, there is general agreement in setting it 1.5 miles (3 km) northwest of Hebron at Rāmat al-Khalīl, an Arabic name which means the “Heights of the Friend,” the friend (of God) being Abraham.
Source: https://www.britannica.com/biography/Abraham/The-Genesis-narrative-in-the-light-of-recent-scholarship

Another article discusses new light on the era of city-states which corresponds more closely to Abraham's time. Among these artifacts are some 20,000 clay tablets found deep inside in the ruins of the city of Mari in today's Syria. 2,000 clay tablets were found in the ruins of Mari, which was located on the Euphrates River some 30 miles north of the border between Syria and Iraq. In its time, Mari was a key centre on the trade routes between Babylon, Egypt and Persia (today's Iran).

Mari was the capital of King Zimri-Lim in the 18th century B.C. until it was conquered and destroyed by King Hammurabi. In the late 20th century A.D., French archaeologists looking for Mari dug through centuries of sand to uncover Zimri-Lim's former palace. Deep within the ruins, they discovered tablets written in an ancient cuneiform script, one of the first forms of writing. Some of the tablets have been dated back 200 years before Zimri-Lim's time, which would place them around the same time that the Bible says Abraham's family departed Ur. Information translated from the Mari tablets would seem to indicate that the Sumerian Ur, not Ur of the Chaldeans, is more likely the place where Abraham and his family started their journey.

The Biblical World notes that some of the Mari tablets use words from the Amorite tribes that are also found in Abraham's story, such as his father's name, Terah, and his brothers' names, Nahor and Haran (also ironically the name for their destination). From these artifacts and others, some scholars have concluded that Abraham's family may have been Amorites, a Semitic tribe that began to migrate out of Mesopotamia around 2100 B.C. The Amorites' migration destabilized Ur, which scholars estimate collapsed around 1900 B.C. Source: https://www.learnreligions.com/archaeological-evidence-abraham-bible-4590053

Although there may be differences of opinion with regard to some dates or the location of some places, there can be no doubt as to the reality of the events, places and customs described in the Genesis account of Abraham.

Answer 2

Internal evidence from the New Testament

This is a Christian site, so a Christian defense for the historicity of Abraham can be based on what Jesus or the apostles say about Abraham. If Jesus / the apostles implied Abraham exists, then there's your internal evidence from the New Testament.

Some examples:

1. Jesus's genealogy in Matt 1:17. Christians believe that Jesus is 100% human and in His human nature He is a natural descendant of Abraham

2. Jesus's claim that he existed before Abraham (John 8:58)

3. Jesus said that many Gentiles will have a feast with Abraham in the Kingdom of God (Matt 8:11)

4. James used Abraham as example of faith in the sense that we can emulate a REAL person from the past (James 2:21-24)

External corroboration from Ancient Near Eastern research

While we have not found a non-Biblical text / inscription naming Abraham, there has been a lot of progress in Ancient Near Eastern research in the past 100 years fueled by new discoveries in the 20th century which both Biblical and secular scholars used to correlate elements of the Genesis story with non-Israelite texts, customs, and material remains.

To answer the claim of Thomas L. Thompson you quoted I offer this excellent essay by Martin J. Selman: "Comparative Customs and the Patriarchal Age" published by IVP in a 1980 book "Essays on the Patriarchal Narratives", listing the current (yet) uncontested correlations between ANE research and Biblical text after reviewing 3 waves of scholarship: 1) Consensus, 2) Destruction of Consensus, 3) Current Discussion. The claim by Thomas L. Thompson was covered in section 2 (Destruction of Consensus), but the essay responded in section 3 with a review of later research that tempered his rather negative assessment.

Another value of this essay is in providing believers with a level-headed and a responsible scholarly (non-polemical) guidelines for comparison (section 3.4 to 3.6). This quote is from section 4 (Conclusion), emphasis mine:

When the biblical and nonbiblical material is subject to proper control, the way is still open for the social customs of the patriarchal narratives to be legitimately illustrated and supported from a variety of historical contexts in the ancient Near East. The following list includes those examples which remain valid in the light of the conditions for comparison discussed above.

... (skipped: list of 12 currently uncontested correlations)

Since the large majority of these examples show that the patriarchal customs can be compared without difficulty with a wide range of material from the ancient Near East, it may be concluded that the patriarchal narratives accurately reflect a social and historical setting which belongs to the second and first millennia BC. More precise dates must of course be derived from other considerations, but neither van Seters' preference for first millennium material nor Thompson's assessment of the essentially nonhistorical character of the narratives can be supported by the evidence of the social customs. From the independent viewpoint of the historian, therefore, the social parallels make the historical existence of the patriarchs more likely.

But our conclusion also has hermeneutical and theological implications. Two examples must suffice. That Laban should conclude the details of Jacob's marriages twenty years after the marriages were agreed (Gn. 31:50), even though a marriage contract would normally have been drawn up at the beginning, is further evidence of his duplicity and of the difficulties with which Jacob had to contend. By contrast, Abraham's refusal to take a second wife or a concubine of his own in the face of Sarah's continuing infertility gives a new insight into his regard for Sarah's position as well as his faith in God's provision of the promised heir. A proper appreciation of the social and historical dimension of the patriarchal narratives thus leads to a more accurate understanding of Genesis' theological contribution, as in the specific application of Abraham's faith.

Answer 3

Embarrassing details: Abraham lied twice to two kings about Sarah being his sister. Gen 12 and Gen 20.

Gen 20 Now Abraham journeyed from there toward the land of the Negev, and settled between Kadesh and Shur; then he sojourned in Gerar. 2 Abraham said of Sarah his wife, “She is my sister.” So Abimelech king of Gerar sent and took Sarah. 3 But God came to Abimelech in a dream of the night, and said to him, “Behold, you are a dead man because of the woman whom you have taken, for she is married.” 4 Now Abimelech had not come near her; and he said, “Lord, will You slay a nation, even though blameless? 5 Did he not himself say to me, ‘She is my sister’? And she herself said, ‘He is my brother.’ In the integrity of my heart and the innocence of my hands I have done this.” 6 Then God said to him in the dream, “Yes, I know that in the integrity of your heart you have done this, and I also kept you from sinning against Me; therefore I did not let you touch her. 7 Now therefore, restore the man’s wife, for he is a prophet, and he will pray for you and you will live. But if you do not restore her, know that you shall surely die, you and all who are yours.”

8 So Abimelech arose early in the morning and called all his servants and told all these things in their hearing; and the men were greatly frightened. 9 Then Abimelech called Abraham and said to him, “What have you done to us?