Paul saw a vision on the road to Damascus. Perhaps it was a revelation, perhaps he was merely insane. But in either case it was a sensual experience. Does anyone know which it was? No. We accept the former or the latter on the basis of various proofs adumbrated in these other categories. And the acceptance of this (or any) knowledge is predicated on a belief in free will--which we cannot even rigorously prove we posses.
As for Platonism, for Jews and Christians (and some Deists, like me) there cannot ever really be any such thing: either these concepts exist in the mind of God, or, they precede him. Since the latter is impossible (for Jews and Christians), ideals have no independent existence not even as concepts. This applies to logic, mathematics, and physics, or course, but also to as metalogic, and metaphysics; and even to the concept of truth itself. For example: I was once asked did the law of the excluded middle (that a proposition must be either true or not true) have an existence independent of God? In other words, in a Godless universe would this concept exist? The answer must be: no. The law of the excluded middle exists because this is the way God's mind works. Independent of Him there is no Truth, and the question about what a "Godless universe" would be like is nonsensical: it would contain no concepts, and would--literally--be unthinkable.
Because of your position against universals, you might be interested in viewing and commenting on this other thread which is actively debating Nominalism v Realism: If a Tree Falls in the Forest...the indivisible link between consciousness and existence.. You and I are polar opposites in that debate. LOL!
Concerning fideism, the Lurkers might be interested in reading more about it over here on Wikipedia. Again, you and I are polar opposites in the debate. But that is good to know!