From James Petigru Boyce’s Systematic Theology:
How does God know? or in what way does he possess knowledge?
1. Not as we gain it, by using faculties fitted to acquire it. There is in him nothing corresponding to observation, comparison, generalization, deduction, processes of reasoning, by which we pass from one step to another, or the contemplation or conjecture of suppositions or theories by which we account for facts.
2. It is even improper to speak of his knowing by intuition, as is frequently done.
3. All that we can say is that his knowledge is his essence or nature knowing. It is not something acquired, but something belonging to that nature itself and identical with it, in like manner as are his love, and truth, and justice. It is something so inherent in his nature that it exists exclusively of any means of attaining or perceiving it, which we call action.
4. The knowledge of God, therefore, not being acquired, cannot be increased. Time does not add to it. Succession of events does not bring it before God. All the objects of his knowledge are to him eternally present and known.