College Press, a publisher in some way affiliated with the Christian Church, offers on their website a
free set of commentaries on the entire Bible.
Called the "Bible Study Textbook Series," these are solid, high-quality commentaries that College Press once regularly sold in a hardback dead-tree version. They apparently have been superseded by a new set of commentaries which are based upon the NIV, have different authors, and perhaps have other major changes. It seems that College Press digitized (to pdf format) the old commentaries and placed them on their website. They indicate that they did this as a courtesy to people who might be interested in them.
These commentaries were first published about 40-50 years ago. However, they are non-technical, so there is little information in them that has changed over that period of time. These commentaries are aimed at the people in the pew rather than clergy.
Among the titles listed on the webpage that I'm about to give you the URL for, are a number of other
free high quality religious books, mainly on doctrinal subjects. Following that link I'm also giving you a link to a webpage with still more non-commentary books (I don't know why they're on a separate webpage).
Here are the links:
Commentaries & Other Books.
More Non-Commentary Books.