God called Abraham before he moved to Haran.
2 And he (Stephen) said, “Hear me, brethren and fathers! The God of glory appeared to our father Abraham when he was in Mesopotamia, before he lived in Haran,
3 and said to him, ‘Leave your country and your relatives, and come into the land that I will show you.’
Acts 7:2-3 NASB
God called Abraham after he moved to Haran.
(11:32) The days of Terah were two hundred and five years; and Terah died in Haran.
(12:1) Now [And] the Lord [had] said to Abram,
“Go forth from your country,
And from your relatives
And from your father’s house,
To the land which I will show you; …”
(12:4) So Abram went forth as the Lord had spoken to him; and Lot went with him. Now Abram was seventy-five years old when he departed from Haran.
Genesis 11:32-12:1, 4 NASB
Intro
The critic claims that Abraham was called in Haran and not in Ur of the Chaldeans stating: “Stephen had no way of knowing what happened nearly 2000 years before he was born. What he "knew" he got from Genesis, and he just got some of the details confused.”
In my view the critic has reached a false conclusion. He ignores the fact that after the death of his father Terah in Gen 11:32 a completely new story begins: the story of Abraham (Gen 12:1).
Comment 1
A new story usually begins with a flashback or more extensive reference to past events, since these often influence future developments. Compare the beginning of the Isaac story with the remark that Isaac was the son of Abraham (Gen 25:19). The story of Abraham begins with a flashback (Gen 12:1-3) to the story of his calling. This was relevant as Abram, when living in Haran had not yet left his family and the land there had become his land (Gen 24:4). However that doesn’t mean that Abram’s calling was given in Haran, only that the calling had not yet been fulfilled by Abram as he was still living together with his family in Haran. Now, after the death of Terah it was time for him to move to Canaan. He was released from the obligation to take care of his old father and the time had come to fulfil the calling God had given him previously.
Comment 2
Later in the Abraham story there is a reference to Ur of the Chaldeans as the place of his divine calling (Gen 15:7) “And He said to him (Abram), “I am the Lord who brought you out of Ur of the Chaldeans, to give you this land to possess it.” There is nothing strange about this. The first part of the fulfilment was undertaken by leaving Ur together with Terah’s departure from Ur. Abraham was an adult then and responsible for his own actions. So he acted in accordance with God’s call to him to go to Canaan with his father Terah (Gen 11:31).
Stephen was right
Stephen was not the only person who referred to Abram’s calling in Ur of the Chaldeans. This had already been stated by Nehemiah (Neh 9:7) and we have to reckon with the fact that Stephen presented here the general Jewish view concerning this matter. Stephen didn’t cause his highly educated hearers to protest with his statement, so we can be sure that he followed common knowledge of the calling in the neighborhood of Ur.
The critic is skilled in criticism, not in correct understanding.
No Bible Contradiction
Compare the article How old was Abram when he left Haran?