Is atheism compatible with the Noahide Laws?

Of the Seven Laws of Noah, only two specifically refer to religiosity (rather than to morality more generally): do not worship idols and do not curse God. Assuming a non-Jewish atheist does not worship idols or curse God, would they be considered as following the Noahide Laws, if they obeyed the other five laws as well? Would this atheist also be considered righteous and to have a share in Olam HaBa? Would this atheist be considered more righteous than someone who practices a religion considered idolatrous, even though they follow the other Noahide Laws and may even have some sort of spiritual relationship with the Divine?