Human knowledge represent constant change or process. Process is something what is not complete or finite but always have phase, continuity and development. Therefore human knowledge can't be whole and perfect but always partial and limited.
Illusion of perfect and finite knowledge are characteristic of arrogance. Arrogance by itself prevent progress in knowledge. Only when are people aware of own limitation they are capable to be open to different ideas or learn and make progress. On that way they also can free them selves of own illusion and prejudices, but in the same time to know that they can form other illusions and prejudices caused by partiality of knowledge.
Proportion of that what we know with that what we don't know about existence is immense to give us right to be confident. Approach to question of existence must have to be flexible or open to consider different and even contradict alternative and thinking.