In his "Discourse on the Cūḷavedalla Sutta," which I am currently editing, the Venerable Mahāsī Sayādaw had this to say about Nihilism:
“The nihilistic view that everything passes into oblivion with the annihilation of existence after death is the result of craving. Because of the acceptance of this view it is believed that after expiry of the present life-term, nothing remains to experience the good or bad results of one’s own actions. Therefore, one who holds this view, also tends not to avoid vices and demeritorious deeds (akusala kamma). Neither will he or she be inclined to perform meritorious deeds (kusala kamma). His or her entire attention is devoted to finding various ways and means to search for pleasures and to possess and enjoy the delights of life. For a person who accepts the nihilistic view of (ucchedadiṭṭhi) (i.e. that death is the annihilation of existence), there is hardly any good kamma to cause rebirth in a noble or worthy existence. Nevertheless, unwholesome kamma is likely to be in abundance. Therefore, getting attached to one of the three death signs (kamma, kamma-nimitta, or gati-nimitta) that will appear on the verge of death, it is probable that he or she will, under the circumstances then prevailing, be driven to the mental state of rebirth consciousness that will drag him or her down to the lower realms (apāya). ”
The gravest danger of this "one life only" view is that it encourages the pursuit of selfish pleasures at any cost, and provides no incentive to abstain from unwholesome deeds, nor to cultivate wholesome ones. Though the non-believer in the doctrine of kamma and rebirth may not be totally lacking in morality, whatever morality he or she has will be conditioned by social norms, which in most societies will involve actions that are immoral or unwholesome from the Buddhist POV.
• • • • (Upasampadā: 24th June, 1979)