You believe that you can know absolute truth with absolute certainty. You also believe that only the Triune God has infinite knowledge. Nevertheless, to believe that you can know absolute truth is also a personal claim of infinite knowledge when fully worked out. In order to know that you can know absolute truth with absolute certainty, you must be certain of your knowledge because of the basis upon which it is built.
This certainty is placed within the mind, which is a physical organ and prone to hallucinations and dementia. It is entirely possible that you are the victim of some mental anomaly that produces hallucinations of the sort that would cause you to believe in certain things with absolute certainty. Yet, if it is based upon a mental anomaly, such knowledge would be entirely unjustified. Finally, since such a mental anomaly is at least possible, and since you clearly can provide no argument proving that you are not underneath some mental anomaly, then you cannot be absolutely certain.
Of course, that's a rather extreme example. I don't think you've got a mental anomaly. You don't think you do either. But it is entirely possible that you do (or I do, or anyone does), and since even one possibility negating the proper development of absolute certainty exists, then the whole of absolute certainty must necessarily come crashing down. We might get danged close to absolute certainty (after all, how can we possibly believe 1 + 1 = 3?), but it is ultimately a circumstance only possible to God in his infinite wisdom and knowledge.
Ultimately, to know with absolute certainty, one MUST have infinite knowledge, for one would need to know that every possibility that would defeat our absolute certainty is not true (that is, you would need to be able to know that you are not under a mental anomaly, which you can not know), and since there are an infinite number of potential possibilities, one must possess infinite knowledge.