This popular children's book tells the story of a mischievous dog named Bongo who gets turned into a human for Christmas. He then has to learn how to be a good boy and appreciate the meaning of the holiday. While it doesn't specifically have God turned into a dog, it does play with the idea of a divine being having a human experience.
Here are some other possibilities, though they might not be quite the same as what you're remembering:
* "The Littlest Angel" by Charles Taze Russell: This classic story features a little boy who dies and becomes an angel, but it doesn't involve a dog or god being turned into one.
* "The Dog Who Saved Christmas" by John Ryder: This book, as mentioned above, has a mischievous dog who is turned into a human, but there's no mention of God.
It's also possible that the book you're thinking of is a lesser-known title or even a personal story someone shared.
Do you remember any more details about the book?
* Was it specifically a religious book, or a children's story?
* Did it have any other distinctive features like a specific style of illustration?
* Can you remember any other details about the plot?
The more information you can provide, the better chance we have of finding the right book!