I suppose if we are going to look at the progress from Atheism to Theism it will make more sense to look at its usual form of Christian Theism as Deists are thin on the ground at the moment. The group that is most likely to have been swayed by intellectual or rational arguments are philosophers. I use the appelation philosopher in a broad sense to cover anyone who has reflected deeply on things. There are a few philosophers that have made the transition from atheism to christian theism among them being Alisdair MacIntyre, A.N. Flew, Mortimer Adler, Ed Feser, Peter van Inwagen, C.S.Lewis, Victor Reppert, Edith Stein, Michael Dummett, Peter Geach and Elizabeth Anscombe. The first 4 seem to have been influenced by rational, apodeictic if you will, considerations; the others passed to belief from a variety of causes as far as I can judge. The reading of St.Teresa of Avila was a factor in the conversion of Stein, mystical experience in the case of Reppert and Lewis. Anscombe claims her reading from the age of 10 to 15 was a factor which could mean lives of the saints or the Summa. I can discover nothing about Geach’s pilgrim’s progress. There does not seem to have been any intellectual argument at play in the case of Dummett only the gradual acceptance of the truth of the Catholic religion. Peter van Inwagen may have become an Episcopalian by osmosis.
By the way I am absolutely open to correction on any of this somewhat broad brush review. On the basis of this minute sample of philosopher swimmers of the Tiber or the Thames it seems that conversion induced by argument comes quite late in life, the vanity of other systems by then apparent.
Dr. Michael Sudduth is disporting himself amongst the billows of the Yamuna led by ananda itself, isn’t it. The path to Eastern religion is overwhelmingly experiential but this is another topic for another day.
How could I have forgotten the names of Jacques and Raissa Maritain who were saved from the fulfilment of their suicide pact by the teaching of Henri Bergson their professor at the Sorbonne. He brought them to a sense of the absolute and some time after that great devotee of the absolute and profound anti-rationalist Leon Bloy brought them into the Catholic Church. Bloy himself through a dramatic conversion had left his own anti-Catholic past behind. Jacques Maritain is of course famous for his Thomistic writing but his thought in my view has elements of the intuitionist approach.
Add Thomas Merton and Bede Griffiths to the list of those who converted to Christianity as a result of mystical experience. Both later became monks, Trappist and Benedictine respectively.
Nicholas Rescher adopted the Pascalian 'fake it to make it'.
Addendum 26/8/13: From Collected Philosophical Papers of G.E.M. Anscombe:
As a result of my teen-age conversion to the Catholic Church -itself the fruit of reading done from twelve to fifteen - I read a work called Natural Theology by a nineteenth century Jesuit. I read it with great appetite and found it all convincing except for two things. One was the doctrine of scientia media, according to which God knew what anybody would have done if, e.g., he hadn't died when he did.