I have never heard any person acknowledge both that God exists and they do not know who he is in the same sentence. I will not say it has not happened before, but in my limited sphere of relationships I have not heard it. What I have heard which has come to be equally profound in a negative way, is people speaking authoritatively when the subject of god came up. With authority we profess to know and with authority we deny his existence. With authority we declare how God thinks, how to get to him, how to become one. With authority we abolish, and banish, and box God according to how we think and feel. These things I have heard in my sphere of relationships.  It would have been a breath of fresh air if someone had conveyed to me that they believed that God existed but they do not know who He is. (That would have put two of us on the same page).
Even the Christian often times misses this point; he accepts Jesus on the basis of the presentation, yet, not knowing if he is real, or if He is the truth. We think He is, we feel he is. That is the extent of our understanding. What one thinks and feels is also the basis of every person’s acceptance of any religion or spiritual portal. At this juncture, the Christian faith seems as just another religion. The new Christian does not know if he has begun a relationship with the true and living God, but at some point he should know definitively yes, or definitively no. People often leave the Christian faith without the definitive yes or the definitive no. God is among gods proliferated by many voices. We live as if no one can know for sure, therefore we believe as we see fit, for no one can prove otherwise. Me being alone and speaking into the air those many years ago, “God I want to know you” looms large in the face of the existence of many religions that have a subtext of many versions formed by ever growing groups of likeminded individuals.
It is impossible to know God outside of Him making himself known to the individual. Unfortunately, this fundamental point is lost and religions are accepted and rejected on some other basis. It is easier for God to make himself known to you than for you to find Him…