Because Truth is not the primary value in reality; anyone who puts Truth first will fail in their quest.
In sum: epistemology, the quest for certainty, the question for solid, unchangeable, objective, coherent, total knowledge is an impossible quest, ultimately; because it is not the ultimate reality - being at most an aspect of reality.
This is because creation is ongoing, dynamic, unfolding, open-ended... creation really is creat-ive.
So the bottom line is that reality is something develop-ing; not something that stands still to be captured and defined.
Knowledge is constrained by beings, e.g. by the perceptions, experiences, cognitive capacities of beings; and beings are developing, therefore beings may in future come to know more.
Christians should not, therefore, be misled into putting truth first; because for us, first is the situation of God's creation, and the mutual love of those who are co-creating with God. There is no truth outside this creation - only chaos. But within creation we cannot expect static and permanent and complete truths; because the situation is one of development.
Even God (the primary creator being) does not and cannot know everything of truth; insofar as God's creation continues to develop; and the actions of co-creating agents continue to change things.
Note: All the above is a consequence of 'polarity' - which is a more abstract and physics-y way of saying the same thing.