Congratulations on publishing your book! It takes a lot of work to get to that point, and now you have another hard job to tackle!
Do you have it formatted and available for distribution through Amazon? If so, they have some good information on the site and will do a bit of promoting for you.
For both bound and electronic versions, I'd probably be promoting reviews in several ways: through blogging, sending it to people who can review it to a large following (like the appropriate department of the New York Times, for instance.) I'd also look for forums where interested people are likely to be. For example, if Godbolt is about God in some way, there may be websites that offer message boards where users talk about their views or discuss the Bible, and if the site permits people to post links, then by becoming an active member of that forum, I may have opportunities to introduce the book.
If you have bound versions, you can also approach local, brick-and-mortar bookstores and see if they'll carry it.