Here is a list of classic theology books for free on Kindle. HT Justin Holcomb.
St. Aquinas
- Summa Theologica, Part I (Prima Pars)
- Summa Theologica, Part I-II (Pars Prima Secunda)
- Summa Theologica, Part II-II (Secunda Secundae)
- Summa Theologica, Part III (Tertia Pars)
- On Prayer and the Contemplative Life
Martin Luther
- Concerning Christian Liberty
- Works of Martin Luther with Introduction and Notes (Volume 1)
- Works of Martin Luther with Introduction and Notes (Volume 2)
- Commentary on the Epistle to the Galatians
- A Treatise on Good Works
- The Epistle of St. Peter and St. Jude Preached and Explained
- Selections from the Table Talk of Martin Luther
- Commentary on Genesis, Vol. II (Luther on Sin and the Flood)
- The Hymns of Martin Luther
- Epistle Sermons, Vol II Epiphany, Easter and Pentecost
- Epistle Sermons, Vol III Trinity Sunday to Advent
John Calvin
Jonathan Edwards
D. L. Moody
- Men of the Bible
- Sovereign Grace: Its Source, Its Nature, and Its Effects
- That Gospel Sermon on the Blessed Hope
William Wilberforce
John Bunyan
R. A. Torrey
G. K. Chesterton
DR. MATT CAPPS 
Reblogged this on The Transforming Word with Dr. Mike Spaulding and commented:
Very good resources at no cost to you via Amazon and Kindle download.
Reblogged this on Hope's Reason.
Reblogged this on Sean Holloway.
Thanks for the list, Matt!
Reblogged this on David's Thoughts on Apologetics, Theology, & Philosophy.