The following two short summaries of Cupitt's philosophy of life are quoted from his books.
The first is from The Last Philosophy (1995), Appendix, and the second (which is shaped more like a theology), is quoted from Above Us Only Sky (2008).
Between Creation out of Nothing (1990), and Creative Faith (2015), Cupitt published several other books which turn into sketches of his whole philosophy. The best of them is perhaps The Revelation of Being (1998). He considers After God and A New Great Story to be, in the end, unsuccessful.
The five books just mentioned are very diverse. Why? Because Cupitt is a philosophical pluralist. There is no ready-made law-governed world out there, no great Order of Reason up above, and no vocabulary that cuts up the world in just the way the world divides itself-up. So there cannot be a single book that gets it all just right, and Cupitt has to convey his ideas though books that are something like art-visions of the human condition. You have to read a few of them, and think about their resemblances and differences to grasp the point. Neither in philosophy nor in theology can there be One True Faith: both of them need to accept and understand pluralism.