This chapter discusses the disagreements concerning the existence of God and examines the question about the existence of God has been the central question in the philosophy of religion, and it has mainly been discussed in a rationalistic way. When the existence of God has been discussed in a rationalistic way, the discussion has been about arguments for the belief that God exists, for example about the teleological and the cosmological arguments. When Richard Swinburne evaluates the probability of the theistic hypothesis, he does so by means of Bayess theorem. Often, rationalistic criticism of religion is just a matter of showing that arguments such as Swinburne's are invalid or insufficient, and it is then claimed that if there are no valid rationalistic arguments for the existence of God, one should not stipulate such a being. The chapter examines how fruitful discussion of religious beliefs is possible.