Torah starts with Bereishis - Why?

Darash Moshe (Bereishis 1:1) In the Beginning G-d created – Rashi explains this according to its plain meaning that in the very beginning of Creation … Furthermore it seems that this is to be understood as the Introduction to the entire Torah. This implies that  it is not considered performing a mitzva unless the person believes that G-d created everything that exists because without this faith there is no fulfillment of mitzvos. And even concerning a nonJew the Rambam (Melachim 08:11) states that observing the 7 mitzvos of the descendants of Noah requires the nonJew as a minimum to have the belief  that they were commanded by G-d through Moshe in the Torah.  One who lacks this basic faith is not considered a wise or pious person – and surely this is required of Jew. Consequently it is necessary to begin the Torah with this critical fact