Dewi Zephaniah Phillips, usually cited as D.Z. Phillips, is recognized for his work in the philosophy of religion and other philosophical disciplines. He was also a proponent of preserving the Welsh language.
This book was very useful especially if one is thinking about how to go about doing a Wittgensteinian analysis of religious belief. Although this book is one of Phillips's immature works (in the sense that he retracts at least a few of his statements about language games and religious belief), it is certainly the best place to begin if one wants to see what has been of yet, I think, the best fruits of a Wittgensteinian analysis of religion. The main import of this book is probably in Phillips's understanding of prayer as something one undertakes as an attitude towards (1) all explanations, (2) the sum of all one's moral endeavors, and (3) contingency. He carries through this analysis in light of Wittgenstein's distinction between superstition and genuine religious belief. I think it is worth the read for anyone who wants to think about prayers in a coherent, philosophical way.