Question: Unbelievers spiritually blinded and also knows there is a God?

Someone asked: Are unbelievers spiritually blinded? If everyone in their heart knows there is a God, how can they be blinded?

This is a question that particularly is one that concerns the Presuppositional Apologists who say nonbelievers in some sense actually know God but are also spiritually blinded.  If someone is not careful, one can think this is an objection to Presuppositional Apologetics.

Here’s my take:

1. First off the Bible does teach unbelievers are spiritually blind. 2 Corinthians 4:4 states “in whose case the god of this world has blinded the minds of the unbelieving so that they will not see the light of the gospel of the glory of Christ, who is the image of God.”  Luke 4:18, Zephaniah 1:17, John 12:40 and other passages affirms this truth.
2. I do think knowledge is known in different ways with different aspects.  For a non-controversial ordinary example consider how the proposition “I know Joe Biden” is something that is true for you and I in that we know he’s the president.  But we can’t go to the White House and tell the secret service you can see him right now…you don’t know him personally in a relational way.  Also consider also knowing how to do something as a skill as another way of knowing.
3. Scripture also recognize different aspects and different ways of knowing.  Consider how Adam knew his wife in Genesis 4:1.  That speaks of intimate relations between spouses.  We may intellectually know Eve was Adam’s wife but not in the way of Genesis 4:1.
4. Scripture talks about salvific knowledge versus nonbeliever knowledge of God.  Romans 1:18 and following tells us nonbelievers know God but it’s not in same sense as That of believers.  Given I established how there are different senses of knowing, we can make a distinction too between believer’s Spirit enlightened knowledge versus unbelievers darkened knowledge.  For believers it involves trust and faith in Christ; not so with the nonbelievers. The nonbelievers’ spiritual blindness mean they choose not to submit to the truth of what they do know, and being darkened Romans 1:23 states they have the desire to manufacture idols to explain away the truth they do know.  Sometimes lies are mixed with some truth in order to appear true and the nonbeliever’s spiritual blindness means the worldview they have will have some grain of truth but clouded with darkness of lies.
5. Sometimes we can know something but also be wrong about what we think we know about our knowing.  I think this complexity is the result of sin’s impact on our mind and epistemology.  For example someone who is a relativist professes all truth is relative and there’s no absolute.  But he doesn’t really know that since he live his life declaring truth and actually believe that truth matters when he gets upset hearing about fake news.  Contrary to his profession he actually knows the opposite of what he claims.  He is mistaken about his belief about beliefs.  One would say he’s suppressing the truth he knows though his thinking is clouded, or shall we say darkened, even when he deep down knows the truth that not all things are relative.