Truth is like an opaque bag with an object inside, but no opening. You can poke, prod, twist, squeeze, kick, hike, spin, sit on, stretch, slam, or feel it through the bag for eternity, but you won’t know for certain what is inside that bag until you take it out, or ask who put it in there (which still involves some doubt, because now you must judge that individual). You may have an excellent idea, but no certainty. What is its color, for example? No one will ever know, while its still inside the bag.

In terms of religion, I would argue that God is inside the bag. You feel him but there is no way of revealing his identity.