First, you need to break the mindset that you can't use your own brain to figure out if something is credible. The church has indoctrinated its members to believe that you can't trust reading anything about Mormonism if its not church approved. Look at the sources being used. Are they being properly cited? Is the citation credible? Are they drawing proper conclusions from what evidence they have cited? Study all sides. Draw your OWN conclusions based on ALL the evidence. You don't have to rely on others to draw your own conclusions.
First, Godmakers is a waste of time, as is most literature out there written by evangelicals. Some of it is good but if you notice most of their chapters consist of comparing doctrinal differences between Mormonism and the Bible then I wouldn't bother.
I would go to
http://signaturebooks.com/ for most scholarly books about Mormonism. They are not written in an effort to be faith promoting but they aren't generally considered "anti" either. They don't hold back on the damning evidence but they also kind of tip toe through it with their conclusions as not to sound anti.
If you were looking for the fast track to obliterating your testimony with credible books, then I would read in the following order:
1)http://mormonthink.com/personalstories/A_Letter_to_a_CES_Director.pdf
2) Mormonism - Shadow or Reality - by Jerald & Sandra Tanner
This book is THE MANGUS OPUS of exposes on Mormonism. It an incredibly exhaustive expose citing nearly every historical document that is a problem in Mormon history. It hits on nearly every topic such as The Book of Mormon, plural marriage, blood atonement, changes in the temple, racism, etc.
That should do the trick, but if you want to further enrichment on the truth of Mormonism, then I compiled a list of credible, scholarly books which I consider the best books regarding learning the full truth about Mormonism. I have placed a star next to my favorite recommendations since most people would obviously not read all of them.
Overall/History/Joseph Smtih
* Mormonism - Shadow or Reality? (or The Changing World of Mormonism) by Jerald & Sandra Tanner
* An Insider’s View of Mormon Origins by Grant Palmer
* No Man Knows My History: The Life of Joseph Smith by Fawn M. Broadie
* The Mormon Hierarchy: Origins of Power by D. Michael Quinn
* The Mormon Hierarchy: Extensions of Power by D. Michael Quinn
Under the Banner of Heaven by Jon Krakauer
Mormon America, The Power and the Promise by Richard Ostling, Joan K. Ostling
One Nation Under Gods: A History of the Mormon Church by Richard Abanes
Joseph Smith: Rough Stone Rolling by Richard Lyman Bushman
Joseph Smith: The Making of a Prophet by Dan Vogel
Joseph Smith: The First Mormon by Donna Hill
The Prophet Puzzle: Interpretive Essays on Joseph Smith by Bryan Waterman
Joseph Smith and the Origins of The Book of Mormon by David Persuitte
The Keystone of Mormonism by Arza Evans
The New Mormon History: Revisionist Essays on the Past by D. Michael Quinn
Mormon Mavericks: Essays on Dissenters - John Sillito and Susan Staker
Polygamy
* In Sacred Loneliness: The Plural Wives of Joseph Smith by Todd Compton
* Mormon Enigma: Emma Hale Smith by Linda King Newell
Mormon Polygamy: A History by Richard S. Van Wagoner
Solemn Covenant: The Mormon Polygamous Passage by B. Carmon Hardy
Nauvoo Polygamy: “… but we called it celestial marriage” by George D. Smith
Book of Mormon
*New Approaches to the Book of Mormon: Explorations in Critical Methodology by Brent Metcalfe
*Quest for the Gold Plates: Thomas Stuart Ferguson’s Archaeological Search for the Book of Mormon by Stan Larson
*American Apocrypha: Essays on the Book of Mormon by Dan Vogel and Brent Lee Metcalfe
Losing a Lost Tribe: Native Americans, DNA, and the Mormon Church by Simon G. Southerton
Book of Abraham
*By His Own Hand Upon Papyrus: A New Look at the Joseph Smith Papyri by Charles M. Larson
Joseph Smith's Treasure Hunting, Folk Magic & Occult Practices
* Early Mormonism and the Magic World View by D. Michael Quinn
Temple
Evolution of the Mormon Temple Ceremony: 1842-1990 by Jerald and Sandra Tanner
The Mysteries of Godliness: A History of Mormon Temple Worship - David John Buerger
Mountain Meadows Massacre
Blood of the Prophets: Brigham Young and the Massacre at Mountain Meadows by Will Bagley
The Mountain Meadows Massacre by Brooks, Juanita
Misc
Line Upon Line: Essays on Mormon Doctrine by Gary James Bergera
Power From On High: The Development of Mormon Priesthood - Gregory A. Prince