I don't know all there is to know. By the time I catch up on one thing, even becoming a specialist, in one area, the discipline develops, the science leaves me behind. If knowledge is doubling every 4 years or faster, then we cannot keep up with what we are supposed to know.
We don't even know all that is important to know. Let's take health for example. How do I keep myself completely well all the days of my life? There are are so many viruses and diseases that we can't handle them. Just when we discover the anti-body a new virus begins.
Or let's take the future. More than anything, people want to know what the future has for them. It would help us to plan accordingly. But our minds are limited.
It takes God to know all there is to know. But it also takes God, for us to know all we need to know and all that is right to know.