Would you mind shedding light on Acts 7:14 [75 souls in number]. Acts 7:14, according to some Rabbis and counter-missionaries, counters Genesis 46:27. They make claims that this is among many of the errors of the B'rit Chadasha. Please, silence this notion especially for those infant believers who by every whim are tossed to and fro.
Thank you for your request! This issue comes up from time to time and many are "quick" to cite "discrepancy" and blame the B'rit Chadasha as "erred"! But that's folly. Yes, there "appears" to be a discrepancy. To wit, the verses you cited:
Genesis 46:27 "Thus all the people in Ya‘akov’s family who entered Egypt numbered seventy."
Acts 7:14. "And Yosip sent for his father and brought Ya’akov and all his family. And they were seventy and ﬁve souls in number."
But let me say right up front: The discrepancy is only in our incomplete knowledge of the numbers presented in the Masoretic Text (the accepted Hebrew Tanakh) and the B'rit Chadasha. To conclude the B'rit Chadasha is somehow in error is the epitome of bias and arrogance. Scholars can't even agree on how the number "70" is arrived at in the Masoretic Text! Is Ya'akov counted? Are the two, named females counted (Dinah, verse 15 & Serach verse 17)?
(From my own counting of the names in Gen 46, I conclude that the numbers presented in the Masoretic Text are at least consistent, that is, "66" is correct in verse 26 because 66 includes all the names of sons and daughters and excludes Ya'akov, Yosef, M’nasheh and Efrayim). And "70" is correct because it INCLUDES all names including Ya'akov, Yosef, M’nasheh and Efrayim. But that DOES NOT mean "70" is "correct" because the Masoretic Text is nothing more than an amalgamation of many ancient documents! The Masoretic Text is NOT from an original ancient Hebrew manuscript.)
So let's look at the number "75" in the B'rit Chadasha, Acts 7:14. The number is presented by Stephen during a speech he made in which he summarized pretty much then entire history of Judaism! Guess what version of the Tanakh Stephen would likely have been familiar with in his time? It would NOT have been the Masoretic Text as the Masoretic Text would not appear for another 800+ years! It would have been the Septuagint from which Stephen was drawing his history!
And the Septuagint differs from the Masoretic Text in Genesis 46! It not only differs in the cited verse 27, but in other verses as well! In fact, verses 20-22 in the Septuagint cite grandsons of Yoseph not named in the Masoretic Text, adding 4 names to the total! So there's a total of 74 without much effort. (The problem is not resolved though. The Septuagint does not account for how it arrived at 75!)
But the Septuagint is probably what Stephen knew, and it said "75"! So, given that Stephen in Acts 7 was likely referring to the Septuagint which (I emphasize) pre-dated the Masoretic by hundreds of years, why aren't the naysayers complaining about the Septuagint instead of the B'rit Chadasha? Why aren't the naysayers questioning the Masoretic Text instead? After all, it disagrees with the far-older Septuagint!
The bottom line? The available manuscripts don't seem to provide enough information to come to a definitive conclusion. The Masoretic Text is biased (being the result of a "committee" of Rabbis who "decided" what was "original" from a number of sources), and the Septuagint is a Greek translation from now-lost original, ancient Hebrew manuscripts, and contains its own biases from the 70 scholars who assembled it!
Is this a "deal breaker"? That is, are we not to believe the B'rit Chadasha because of Acts 7:14? Of course, I would say "no", but if someone insisted, I'd simply point out to them the shady origin of the Masoretic Text and demand they prove its in-errancy.