I intend not to delve too far into the problem. Only make a few comments as the definition relates to Christian beliefs.
First, the nature of truth. Christian Theism (CT) holds that God knows differently to human beings. God knows comprehensively and exhaustively. God cannot be mistaken in any of what he knows (since to be mistaken is not to know). Truth, therefore, is certain in relation to God. This is because God, as it were, determines truth, all of it. This means that truth is ultimately taken care of – whatever can be known is known by God.
Second, the nature of human beings. It is clear, at least to most of us, that human beings do not have knowledge in the sense that God has it. We neither know comprehensively nor exhaustively, nor do we determine what is true. Human beings do know God and know that we are created by him. Some human beings know God’s favor and have received special knowledge through the the revealed word of scripture. They are related to God in a way that has an effect on their knowledge.
In some sense, then, one would expect knowledge to be less reliant on justification than we first thought. If truth is determined (by God), then truth, in some sense, is taken care of, sealed up. God himself doesn’t know truth through justification of his beliefs. What is true, rather, is what God believes. He does not need any external method of justification. Something is true because God believes it.
This is not true of human beings. We are not in anything like the same position as God. However, the two relate in certain ways that make human beings able to come to knowledge. First, God designed human beings with the capacity to form beliefs. Notice that God’s ability to do this relies on God’s having got truth wrapped up. It would not be possible to design human beings with the ability to know anything without knowing everything. This is because if God’s knowledge was in anyway limited there would be no way to know just how limited it was. It may be that even God’s knowledge is only very limited and that there is far more not known than known by God. If that is the case, then God would have no way to guarantee that what he already knows is true (since something that he does not know might challenge what he already takes to be knowledge) and there is no way to guarantee that how God knows is a valid method of knowing (since, if there are things that God does not know, then how he knows would be cross-checkable with things he does not know and that would require a method of knowledge something akin to inference or observation).
Second, God reveals knowledge to human beings. God, being the creator of human beings, designs them in such a way that their knowledge is contingent upon divine revelation. This explains the human ability to know anything. Knowledge is possible for human beings because it is guaranteed in God. God’s revelation of truth to human beings combined with their being designed to be able to come to true beliefs means that human knowledge is possible. Praise God.
The fact that human beings do not believe some truth in no way impinges on the argument. Since God has revealed himself in scripture and scripture is true we know why it is that human beings do not easily believe the truth. The broken nature of human beings subject to post-fall epistemic conditions renders human belief askew from the truth. This is combined with the stronger notion that human sinfulness has, as its root, unbelief. Knowing God as he is clearly perceived is conditioned by suppressing such truth in unrighteousness.
If knowledge is something like justified, true, belief, and there was no god, then knowledge is never sure. Skepticism is the logical conclusion. Why? Because, what is deemed to be true is what is justified belief. That is to say truth is reach via the justification of belief. But, if knowledge is limited (finite and subject to failure), then there is no way to guarantee the possibility of that truth. In other words, while one might think a belief is as justifiable as is humanly possible, there is no guarantee that it is true. It is only if, in principle, truth is sealed up, known and determined fully, by someone who is able to design a finite knower and provide knowledge to that knower that human knowledge is possible. Again, the fact that human beings can know anything is possible only because God already knows everything.
