Do Atheists Admit To The Entire Torah?

That would be the implication of this statement on Nedarim 25a:

לישבעו דליקיימו כל התורה כולה משמע עבודת כוכבים
דאמר מר חמורה עבודת כוכבים שכל הכופר בה כאילו מודה בכל התורה כולה

Let him {=Moshe} adjure them to fulfill all of the Torah in its entirety? This has the implication of {avoiding the sin of} idolatry. For Master said: {The sin of} idolatry is so grave a violation that anyone who rejects it {idolatry} is as if he admits to entire Torah.

For atheists do not believe in God, but by extension not in any other deity. And this seems to have {on some level} the same status as fulfillment.