I remember the description as follows:
- Jesus and God Christ (Christ is used as a family name) go on a holiday (golf, maybe?) and leave an AI in charge of creation
- Jesus' brother (Kevin Christ?) is insulted at not being left in charge and argues with the computer.
- Jesus' brother decides he can run things just fine and starts pushing some buttons on the computer, which naturally wreak havoc all around Creation.
It might be by Terry Pratchett, or else someone who would have a similar style (with apologies to true Pratchett fans who will say that there is no one else with "a similar style").