as a hindu i think that without believeing in G-d, not much would change materialistically(u can confirm this by looking around at some very rich self hating businessmen). but the next birth would put the soul in lower stratas of life, like mentally disabled human,animals,insects....etc. Human birth is to serve G-d.
i also dont believe in miracles through prayers, like some religions claim to cure diseases,illness by prayers. Prayers do not make an amputate person grow their limbs back, but stem cell research does!