“Zealot: The Life and Times of Jesus of Nazareth is a book by Iranian-American writer and scholar Reza Aslan. It is a historical account of the life of Jesus and analyzes the various religious perspectives on Jesus as well as the creation of Christianity.”
https://en.m.wikipedia.org/wiki/Zealot:_The_Life_and_Times_o...
Surely not any Christian or any atheist. Not any Muslim either. I suppose Buddhists wouldn't have any particular stake in whether a historical Jesus existed.
The consequences of being able to prove with certainty either that Jesus existed and is who Christians claim him to be, or did not exist or was not divine would have tremendous consequences on the lives of hundreds of millions people who do not ascribe to the proven belief.
They could say "I am intellectually honest and will change my beliefs depending on the evidence," but we both know that 1. Concrete evidence strong enough to convince someone to change their beliefs, beyond what is already known, likely does not exist. And 2. Their current beliefs already match their known evidence so any additional information is unlikely to radically change their beliefs, only be accounted for and integrated into their current belief system.
I'm not trying to say all scholarship is biased or we shouldn't believe anything. In all likelihood, most people are not deliberately lying or falsifying anything.
What does that mean about which scholarship to trust? I have no idea.
Christians (ignoring some defunct or very rare forms) have it as an article of faith that Jesus was a real historical human who was also divine.
Atheists would deny that Jesus or anyone else was God, but there is nothing about atheism that is opposed to duly considering possibly trustworthy evidence that the Jesus whom Christians believe on faith was/is God may have indeed existed as a real historical human.
At the same time, unlike (for example) Muslims who believe Jesus was a human prophet but not himself divine, atheists don't have any specific belief about Jesus's human historical reality at all. If the evidence shows that he was made up by combining bits of multiple people's teachings, atheism is unaffected.
Therefore, an atheist's writing about this question is, all things being equal, more likely to neutrally consider all the available the secular observable facts about the question, without influence from religious motivations, than a Christian's.
However, that italicized precondition is usually false.
Real writers vary in their approach to scientific and historical rigor, being imperfect humans themselves and not abstractions. So an individual Christian could well be a more trustworthy source on this than an individual atheist, or vice versa.
As for his book, I realise that book publishers like to give their products sexy titles, but the title can't possibly be paid out in any non-fiction sense as we have exactly zero contemporaneous written accounts of Jesus' life. Anything he has written could only be a further digestion of the already contentious writings haphazardly collected into the book we now know as the Christian bible.
https://www.kcl.ac.uk/artshums/depts/trs/events/jandb/index....
https://soundcloud.com/kings-college-london/jesus-and-brian-...