'Suppose there is a hereafter and there is a fruit, result, of deeds done well or ill. Then it is possible that at the dissolution of the body after death, I shall arise in the heavenly world, which is possessed of the state of bliss.' This is the first solace found by him.
'Suppose there is no hereafter and there is no fruit, no result, of deeds done well or ill. Yet in this world, here and now, free from hatred, free from malice, safe and sound, and happy, I keep myself.' This is the second solace found by him.
'Suppose evil (results) befall an evil-doer. I, however, think of doing evil to no one. Then, how can ill (results) affect me who do no evil deed?' This is the third solace found by him.
'Suppose evil (results) do not befall an evil-doer. Then I see myself purified in any case.' This is the fourth solace found by him.
The disciple of the Noble Ones, Kalamas, who has such a hate-free mind, such a malice-free mind, such an undefiled mind, and such a purified mind, is one by whom, here and now, these four solaces are found.”
(Buddha, Kalama Sutta)
One of the central teachings found in Buddhism is that of rebirth; that after death certain aspects of the mind reappear in subsequent births. Mainstream modern science (currently) denies that rebirth takes place, and this belief is seen as supernatural. On the other hand, many Buddhists argue that the belief in karma & rebirth is essential to Buddhism, and without it Buddhist practice ceases to be truly Buddhist. However, the Buddha himself seems unconcerned with holding such a view (and, in other places in Buddhist scripture the Buddha is said to be one that is free of all views). As the quote above shows, he stills sees it as worthwhile teaching the Kalama people even if they don’t believe in rebirth, stating that there are still benefits to be had from ceasing unwholesome actions and taking up wholesome ones in this very life.
These benefits include being “free from hatred, free from malice, safe and sound, and happy” and that by not doing harmful acts any harmful results thereof will also be avoided. These are pretty worthwhile aims in this life, so even if the ultimate objective of nirvana seems far of, there are still worthwhile advantages in practicing Buddhism. Who doesn’t want to be free from hatred & malice, to feel safe & be happy? Personally, I can vouch that by following these principles an increase in confidence & happiness can follow. Furthermore, if practiced in conjunction with other aspects of Buddhist practice such as meditation, a genuine, deep sense of calm contentment can arise, allied with a conviction that life is being lived in a worthwhile way.
In conclusion, then, the question, “To be reborn or not to be reborn” doesn’t seem quite so crucial to Buddhist practice. There’s no need to reject it out-of-hand and attach to the belief that rebirth is impossible, but neither is a lack of belief in rebirth a block to progress on the Buddhist path. In the end, Buddhist teachings exist as upaya (skillful means) to assist us to lead more wholesome lives and in our progress to the realization of nirvana. We should use those teachings and techniques wisely, and, simply by living what the Buddha describes as a wholesome life, we will reap the benefits in this very life… and maybe beyond!