Hadran Al Harambam 5735

Every mitzvah has 2 parts. What you do and what it is not. For instance, Teffilin. Making and putting on Teffilin and not being just a piece of leather.
The most important Mitzvah also has to parts. Believing in Hashem and believing that He cannot not be.
That is why we heard the first 2 of the Aseres Hadibros and it was not enough to hear just the first, which seemingly includes the second. Because in the main mitzvah we need to stress both points.
This is also the reason why the Rambam says: "To know there is a first existence" and in the second halacha "And if it will arise in your mind that He doesn't exist, then nothing else could have existed". He points out both aspects of the mitzvah.
Now being that in the mitzvah of believing there are 2 parts, in reality there are as well these 2 'parts' by Hashem Himself. He exists and He doesn't exist. In the words of the Rambam elsewhere "He exists not in existence".
[The Rebbe clarifies that we have no other way of defining that which is not 'not', that which is not 'he'eder'.]
This explains why the Rambam uses the expression "And if it will arise in your mind...", it is actually a higher understanding. But yet if that where the only 'way' Hashem 'is', that He doesn't exist, than nothing else could have existed either. So Hashem has to exist in order for everything else to exist. By the way that's why the Rambam calls Hashem the First existence, even though that first means there is a second and why would he imply that there is a second to Hashem? Because that's exactly his point. His existing is the first for other existences.

At the end of Rambam when he talks about Melech HaMoshiach, he ends the final chapter with: "In that time there will no longer be any hunger... For good will be poured plentifully and delicacies will be found like dust". And he concludes "We will not occupy ourselves except in the knowledge of Hashem..."
Here we also see 2 parts.
1. The not. No hunger, war, strife etc. For the good will be abundant. We will not occupy ourselves...
2. "(We will occupy ourselves) in the knowledge of Hashem..."

Also in knowing Hashem there are 2 aspects:
1. "Knowing hidden things (devarim setumim)".
2. "Understand the knowledge of their Creator, according to human ability".
We will understand the most hidden of things, Hashem's nonexistence. Yet it will be combined and unified with knowing Hashem's existence. And therefore we will still be able to exist even though we know Hashem's nonexistence.

How can we combine both these 'things'? Why of course, from where He is higher than both.