Regarding the Ramabam it’s in Hilchos Teshuva Perek Hey Halacha Hey.
The Ravad there happens to take a strong stand against what the Rambam seemingly writes.
Rav Shach in Avi Ezri has a fascinating explanation of that Rambam and continues with a very fundemental explanation of Emunah.
Rav Shach writes clearly that Belief in G-d is a logical conclusion and not what emunah refers to.