The whole revisionist enterprise is nothing but an ad hominem attack.
Before you use terms like "ad hominem" you should learn what they mean.
In this case and "ad hominem" is an attempt to discredit/refute and idea by refering to who stated it. That is I might say General Relativity can't be right because Einstein was a womanizer.
If however, I show that the idea put forward is wrong then I have attacked the idea and, perhaps, indirectly the brilliance of the individual putting it forward. This difference is that the target is the idea not the individual. If the target is the individual, in an attempt to discredit an idea then that is an ad hominem.
If certain scholarly work suggests that generation of believing Christians do not have good evidence for the historical veracity of those beliefs or that some scholars have not used all available evidence or good logic in arriving at some conclusions that is NOT an ad hominem. Any conclusions that are drawn about the individuals is only drawn based on the quality of their support of an idea. This is not the same as thinking that you have argued against the idea by attempting to show that there is something wrong with the individual.
(As a small aside, since I'm sure you will have trouble with fine distinctions: I may say when an idea is put forward: "Oh, you want to believe something that Hovind says?
" and suggest that the idea is wrong.
If I think that refutes the idea I have committed an ad hominem. However, if all I mean is that, given the past history of that source, we should put extra effort into examining it before giving it any credence then all I have shown is an ability to spend my time effectively by considering the source of information. )