I got this one today on the forum I debate on and I’m sure many other people have got this one as well. “You can’t trust the gospels. After all, the writers were biased.” (Note that the writer of such a statement never considers that he must be biased against documents that he considers biased.)
Let’s be clear. First off, the question of bias doesn’t necessarily matter. What? That’s right. It doesn’t necessarily matter. The first question you ask about any document is “Is the claim true?” Now if you have to go beyond that and look at the credibility of the author, then you do so. However, the first place to start is the truth of the statement itself.
However, there could often come a time to check the credibility of the author. This will many times involve checking to see if the author, if he is a modern one, is credentialed in the area he is writing in. (You obviously can’t check to see if Plutarch has a PH.D. in history for instance.) Is there a reason that we should trust him as an authority?
Then, we can check data within the document itself. Does the document remain true to itself? Even if the whole thing is wrong, is it consistent within itself? Consistency is not a test for truth, but inconsistency can show an untruth in the position stated. It does not mean the whole idea is false, but that one aspect of it is.
We can then check outside information. Was it written fairly close to the event? If it is a modern account, does he use sources that are close to the event? How about archaeological findings? Are there any that back these documents? (For the NT writings, these are abundant and the sources are very close.)
We should also note that everyone has a bias. This doesn’t mean that everyone has a bias in every subject, but if you hold any stance on any subject, then you have a bias for it. If you write your opinion anywhere on any topic, then you have a bias towards that opinion. This is neither good nor bad in itself. It is good to hold a stance, but it is bad to hold it if you are unwilling to examine outside views.
Now we get to the main point. Can bias affect an argument? Indeed! However, it can affect the argument in a good way or a bad way. Suppose I want to really prove something to you. I am biased that my view is correct. However, if I want to make a convincing case, would it be best if I do my research and writing sloppily, or if I take my time and examine the information closely and write out my thoughts in a coherent matter?
When it comes to the NT, we see the writers doing this. Luke especially says that he thoroughly examined everything to be sure of what he wrote. The writers of the NT also had nothing to gain from their writings other than shame and being outcasts from the community at large and persecution at the hand of Nero. Those are hardly compelling reasons to write unless you believe what you write is true and important!
Someone might ask why there are no non-Christian sources to the resurrection. The answer is simple though! If someone who wrote did believe in the resurrection, then they would be Christians! You might as well ask why strong theists don’t write books in favor of atheism!
Overall, the bias argument is simply a red herring. It accomplishes nothing except ignore what really matters, the truth about the topic under discussion.