Dr Francesca Stavrakopoulou asks whether the ancient Israelites believed in one God as the Bible claims. She puts the Bible text under the microscope, examining what the original Hebrew said, and explores archaeological sites in Syria and the Sinai which are shedding new light on the beliefs of the people of the Bible. Was the God of Abraham unique? Were the ancient Israelites polytheists? And is it all possible that God had another half?

Atheist and scientist Richard Dawkins visits England, America and Israel interveiwing prominant people of faith; Islamic, Hasidic Jews, and the new Christian sects popping up throughout the world, and expressing his view of the extent to which this fanaticism has degraded our civilisation, and will continue to degrade it. "The God Delusion" explores the unproven beliefs that are treated as factual by many religions and the extremes to which some followers have taken them. Dawkins opens the programme by describing the "would-be murderers ... who want to kill you and me, and themselves, because they're motivated by what they think is the highest ideal." Dawkins argues that "the process of non-thinking called faith" is not a way of understanding the world, but instead stands in fundamental opposition to modern science and the scientific method, and is divisive and dangerous.

In part 2, we take a look at Odysseus, whom Homer made famous in "The Odyssey," including his adventures in light of astronomical and geographical evidence which bases the story on accurate real events.

Salvador Dali's strange crucifixion is often called the greatest religious painting of the 20th century. Yet its artist was a notorious blasphemer some of whose work had outraged the Catholic Church. The Christ of St John of the Cross by Salvador Dali is the first of two extraordinary crucifixions painted by Dali in the early 1950s. The painting is based on a 'cosmic dream' Dali is said to have had, in which the nucleus of the atom was a figure of Christ himself.
The painting offers a surrealist view of the crucifixion of Christ, and is based on a drawing by the 16th century Spanish friar Saint John of the Cross. But Dali's vision was somewhat unique, using an unusual artistic perspective in which Christ is seen from above. His Christ of St. John of The Cross was inspired by a weird mix of Spanish mysticism and nuclear physics, with his Christ being modelled by a Hollywood stuntman. It's also a masterpiece of painting technique.

The Pythagorian philosopher Plato hinted enigmatically that there was a golden key that unified all of the mysteries of the universe. It is this golden key that we will return to time and again throughout our exploration. The golden key is the intelligence of the logos, the source of the primordial om. One could say that it is the mind of God. With our limited senses we are observing only the outer manifestation of the hidden mechanics of self similarity. The source of this divine symmetry is the greatest mystery of our existence.

In the fourth part of the series, Diarmaid MacCulloch makes sense of the Reformation, and of how a faith based on obedience and authority gave birth to one based on individual conscience. He shows how Martin Luther wrote hymns to teach people the message of the Bible, and how a tasty sausage became the rallying cry for Swiss Reformer Ulrich Zwingli to tear down statues of saints, allow married clergy and deny that communion bread and wine were the body and blood of Christ.