I would be a rich man if I had a dollar for every time a Christian apologist used the above statement as “strong” evidence for the Resurrection of Jesus. Let’s look at this claim using an analogy:
Imagine if a group of UFO experts in the United States were to make this announcement to the news media:
These experts claim that they recently came across four anonymous books that detail the statements of a few hundred people in rural Japan in 1972, who claimed to have encountered little green space aliens, over a one month period of time; odd creatures with long, thin antennas sprouting out of their tiny heads, who claimed to be from the planet Mars.
These experts assert that no Japanese person would ever believe in green, antennae-sporting, space aliens unless they had actually seen them, so the fact that some Japanese DID believe this story, is proof that the story is true.
What is wrong with this reasoning?
Answer: We know that the overwhelming majority of Japanese people in the 1970’s and today do not believe in little green Martians with antennae, therefore, the fact that a small group of mostly rural Japanese do believe this claim, while the overwhelming majority of Japanese remain unconvinced of the veracity of this story even though SOME Japanese do believe it, demonstrates that “no Japanese person would believe this claim unless it is true” is an inaccurate generalization.
Likewise, the claim that “no first century Jew would believe in a resurrection if they had not actually seen it” fails because the majority of first century Jews did NOT believe this story, even though they were aware that a small group of Jews did.
In conclusion, just because a small group of people in a particular society chooses to believe a very odd, shameful, never-heard-of-before belief is not proof that the belief is true. It is only proof that human beings are prone to believe almost anything given the right circumstances.