The Bible tells us that people can be deceived. In fact, it argues that the whole world, apart from Christ (remember that part), is deceived and under the control of the devil.
Now, here is my question for you.
Do you believe that the whole world is capable of essentially getting reality right, but getting Christ wrong? In other words, do you believe that if one's view of God the Father and His Christ is distorted that reality can still be understood?
Do you believe that if one is deceived about God the Father and His Son that reality is impossible to understand?
In essence, to sum up the question, is truth concerning God necessary to understand all of reality, or can reality, for the most part, be understood apart from Him?
How you answer this question will say a lot of what you think about God. If God is the center and foundation of all knowledge and understanding of reality, and one is deceived about the truths concerning Him, then it is not possible for one's view of reality to escape complete distortion.
But if God is ad hoc to your view of reality, if He is not really essential and foundational to it, as is the case in the mind of so many people today, then one can be merely deceived about the truths concerning Him, but have an essentially correct view of reality.
I think this is a huge dilemma for people who argue for a view of reality based on what unbelievers/apostates/heretics say, especially in arguing from consensus.
Now, obviously, this refers to non-empirically verifiable elements of reality (although one might be able to make the case for all things, I'm not going to press it that far today). One might argue that the unbeliever's view of the reality of empirically experienced phenomena is verified by the believer and the unbeliever's adoption of certain assumptions that really only belong to the believer.
But the point is that when one considers non-empirically verifiable phenomena, whether one thinks that analysis of unbelievers and those believers who have relied upon their analysis is still valid has much to do with whether one thinks that deception about the truths concerning God can be compartmentalized due to the knowledge of reality having no reliance upon those truths as its center and foundation.