'Your God is too Small' is a classic book by JB Phillips. It's 50 years old now but still relevant to today's church. It's in two parts: the first outlines several ways in which people misunderstand God, seeing him perhaps as purely a negative authority, or perhaps (at the other extreme) a cuddly refuge. He explains 12 such misconceptions in some detail. The second half of the book looks at who God really is, and what we learn from Jesus.
Phillips is sometimes criticised for his theology, but I can't fault this book other than perhaps being a bit short. Then again, it was quite thought-provoking, and I found that I didn't want to read more than about ten pages at a time, so perhaps it's just as well that it was only 126 pages.
Recommended to anyone - Christian or not - who wants to know more about how people see God, contrasted with who we believe he really is.
Longer thoughts about this book are on my Abstractions blog.