Eli Bendersky's website This is Steinbeck's second novel, published in 1933. It tells the story of the Wayne family - 4 brothers, farmers who moved to California from the east, focusing on Joseph, who came first and established the farm after the death of his father.
True to Steinbeck's style, the main theme of this book is the land of California, and the special connection of the farmer to it. But there's also another major theme, which is religion. And it's not "normal" American religion (protestant Christian), but a weird mixture of it, with ritualistic customs of local Indians and self-made worship of the land, animals and trees. Steinbeck tries to explore the topic of religion in this book, and although I felt he's trying to get somewhere, I couldn't quite figure out where.
And overall, I liked the book less than other things by Steinbeck. Objectively, I can go as far as saying that this is the first Steinbeck's book I didn't really enjoy. Something in it is strange and unfinished, and I know myself for the strong dislike of anything mystical, so it's not a surprise I didn't connect with the plot.
One thing I did like in the book is the character of Thomas. His connection with animals and very unique character is described beautifully.
To conclude, I wouldn't recommend "To a God Unknown". IMHO it doesn't present Steinbeck in his best light.