MW13, Gavra, et al –
MW13 said “Being ‘moral’ only because you have decided that it is the right thing to do is worth nothing.” Well, yes and no. Certainly there is schar in this world and this is the reward of the individual in question(I believe Gavra stated this above). Something we’ve neglected to note (and much more importantly), is that if this person truly does leave a righteous life (albeit without G-d), then potentially through this non-believer’s deeds/morality he merits some siyata d’Shmaya through which he comes to belief in G-d. In all likelihood, this may be some of this person’s “schar” in this world ie greater assistance in recognizing Hashem’s existence.
Ultimately, I don’t think we can belittle the merit a mitzvah/good deed/moral lifestyle, whether or not he is a believer. It may very well be that he returns to Hashem through the merit of these mitzvahs/good deeds/moral lifestyle. As we all know, Hashem is faithful to repay reward and what greater reward can there be for an individual than to come to the solid belief and knowledge of the existence of HaKadosh Baruch Hu.