Yes, Maimonides writes: “The first mitzvah is His command to us to believe in the Divinity. That is, that there is a transcendent essence which is the cause of everything that exists. "I am the Lord your God (Ex. 20:2)" is a statement of this command...” This is actually the first of the “Ten Commandments”.
You ask: "What is the point of such a commandment? Either you believe or you don't. If you do believe, then everything else will follow; but if you don't, who is commanding you to believe?"
I’ll even strengthen your question. How can God command the average person to believe something that a genius the likes of Aristotle chose not to believe?
In his response to these questions, Rabbi Elchanan Wasserman points to an intriguing expression in the Torah: "Do not follow the desires of your heart (Num. 15:39)".
Our Talmudic Sages comment that this verse warns us not to stray from our belief in God. Rabbi Wasserman asks, “Why the heart? Why not the mind? Why don't our Sages tell us not to make the intellectual mistake of heresy? What does the heart have to do with not believing?”
He answers that belief in God is Mankind's "natural condition." In lieu of external influences, every person would cling to this faith, and heresy would not exist. However, there are countless distractions and provocative challenges to our moral integrity. These opportunities for forbidden pleasures act as a bribe to our intellect. Suddenly our judgment becomes blurred, and we find ourselves looking to justify the illicit behavior. Not far down that path is the porthole to disbelief. The Torah's command not to follow the desires of our heart is a warning to not take the bribe offered by temptation, because its end is in apostasy.
Conversely, when the Torah commands us to believe in God, it is commanding us to nurture our natural sense of the Divine — to bolster the foundation of our relationship with God.
