In fact, process theology is difficult to define because process theologians are so diverse and transdisciplinary in their views and interests. John B. Cobb, Jr. is a process theologian who has also written books on biology and economics. Roland Faber and Catherine Keller integrate Whitehead with poststructuralist, postcolonialist, and feminist theory. Charles Birch was both a theologian and a geneticist. Franklin I. Gamwell writes on theology and political theory. In Syntheism - Creating God in The Internet Age, futurologists Alexander Bard and Jan Söderqvist repeatedly credit Whitehead for the process theology they see rising out of the participatory culture expected to dominate the digital era.