How can anyone know God? Only through what he has chosen to make known.
Everything else is guessing.
Penn and Teller sometimes perform an illusion and then show you how it
worked. That is what the word revelation means - information handed over
that you could not have had otherwise.
The Belgic Confession says God gives it two ways. First by the creation,
preservation and government of the universe, which stands before our eyes
like a beautiful book in which all creatures, great and small, are his
letters. Second, and more clearly, by his holy and divine word.
Psalm 19 is built in exactly those two halves. The heavens declare the
glory of God. Day pours out speech to day and night reveals knowledge to
night, and there is no language in which their voice is not heard. Then the
psalm turns, and the second half is about the law of the Lord - perfect,
reviving the soul; sure, making wise the simple.
The sky can tell you that God is. It cannot tell you his name, or what he
asks of you, or how you might be saved.
For that, somebody has to speak.