If my title has you thinking that this is another "Stranger in a Strange Land", it is and it isn't. There's a lot less sex, and a lot more action. Heinlein was doing an analysis of religion and society, with the story a means of getting it across. Steele's book is not such a set piece, but emphasizes the story more. So "Thou art God" seems a little more believable here.
This book, unlike the two books immediately preceeding it in the Coyote Universe ("Spindrift" and "Galaxy Blues"), is set almost entirely on Coyote. If you have not read the first three books ("Coyote", "Coyote Rising" and "Coyote Frontier", you will be missing a lot of background, but you could probably make your way through. You might want to check out the coyoteseriesdotcom web site. (I have not really checked it out, but Steele does mention it).
However, there is a connection to "Galaxy Blues" because in that book we learn of the importance to the aliens that were encountered in "Spindrift" of a particular set of ethical/philosophical principles. Knowledge of this is introduced more fully in "Coyote Horizon", and how people react to it is a central theme. Coupled to it is the idea of the impact of the existence of aliens on some earth religions, particularly Judeo-Christian fundamentalism.
Like the other Coyote titled books, this one is episodic. We start with Hawk Thompson, some years after he killed his abusive father. He has spent time on a work farm and is now employed as a customs inspector, but has no hope. He finds a friend, Melissa, when he saves a prostitute from an abusive john. He also assists in the capture of a dangerous man (we don't know how dangerous until later) who vows revenge on Hawk.
But everything changes when Hawk is the customs agent chosen to meet an alien ambassador. Despite almost triggering diplomatic outrage, or because of it, Hawk receives a gift from the alien. It is the electronic "book" (the Sa'Tong-tas) which discusses the aliens' ethical/philosophical position. Hawk listens(the book may be a form of AI), and leaves with Melissa for some place where he might get answers. Since he is still on probation, he is now a fugitive. During this episode we see that there is significant immigration from earth to Coyote.
The next episode is about Sawyer Lee, who leads hunting expeditions of tourist-hunters from earth to bag a boid, Coyote's most feared land predator. He returns from such an expedition to find that Morgan Goldstein, probably the wealthiest human in the universe, wants Sawyer to help find a former employee of whom Goldstein was very fond. That expedition leads to a wilderness area where the Joseph Walking Star and his companions (thought to be addicted to a drug injected by "pseudo-wasps") have settled in. In the end, a "monastery" is to be built for these folks, who have found something very important.
The next episode gets closer to the heart of things. A "Dominionist" (something like a roman catholic, but not exactly so) cleric arrives in a response for help from a Reverend Rice of his church. The church has lost all but a very few of the former believers. A discussion follows, but the gist is that people don't accept a religion that declares that only Man counts with God. There is an alien delegation from a more advanced civilization, and the aliens reject the notion of a God as posited by humans. Those who were Dominionist have switched to other less species specific faiths or simply don't accept human religion. Reverend Rice has spoken with the Alien cultural envoy and comes away angry at "blasphemy" but also realizing that he no longer has faith either. This infuriates the visiting cleric.
The next episode involves the meeting of Hawk Thompson with the group in the wilderness. Transformations all around.
Next, Sawyer Lee embarks on a voyage around Coyote aboard a scientific vessel. Think Beagle or Challenger type expeditions. During this period, we learn of a change in government of one of the largest powers back on earth. The way is cleared for even more immigrants to arrive on Coyote.
Next we find Hawk, a pregnant Melissa, and Jospeh Walking Star traveling around, spreading the word of the Sa'Tong-tas. Hawk now goes by the title, chaaz-maha (teacher). And teach he does. It is clear that this is not a religion, but an ethical/philosophical stance.
Let me say a few words about it.
First, it is posited that every race has its own version of a God (or gods) creating those races as a divine act.
Once you start meeting other races you realize that you create God, not the other way around. So you are God, and so is every other being you meet.
From there it is essentially the Golden Rule, with some specific codicils that remind me of Asimov's three laws, extended to any thinking being.
It goes beyond that of course. One must learn how to think of others and how your actions toward them should be framed. This section of the book provides some good examples. I have simplified how all this occurs. People are skeptical of this new system, and always assume it is a new religion.
By now, Coyote is being flooded with refugees from earth. The chaaz-maha convinces the people of the village he is visiting to help with relief efforts and he also teaches. Since he has returned to the where he fled earlier, arrest is to be expected.
I won't say more about what follows. Some good is done, some evil is done.
A sequel, "Coyote Destiny", is promised by Steele at the beginning of the book.