There are two tragedies in life: to live life believing God exists, and finding this to be an illusion, and to live life believing God does not exist, but finding that God does exist. Nonbelievers readily concede that belief in God is the more hopeful cosmovision, but the issue is if, in fact, this belief corresponds to reality. But can anything new be said on the issue of God's existence? Rather than arguing deductively, as is typical in philosophy, Belief or Unbelief innovates by following an inductive approach, as is typical in science, where it infers the existence of God as more reasonable in the light of philosophic considerations and the findings of modern science. Inferential arguments sacrifice rigor and definitive conclusions, but rather aim at arriving at the likelier conclusion. Belief or Unbelief concludes that belief in God is not only a more hopeful cosmovision than unbelief, but that it is also the more reasonable inference. It is addressed to intellectually curious and open-minded lay persons, believers and nonbelievers, courageous enough to reexamine their basic convictions.