All 66 books in the Holy Bible
I do not necessarily agree with everything in the following books but they have much to offer
Uncommon Bible Studies by Daniel E. Loeb click Here to read it now
Eusebius' Ecclesiastical History Translated by C.F.Cruse click here to buy it Click here to read it
What the Bible Teaches by R.A. Torry click Here to read it now
Systematic Theology by Wayne Grudem click here to buy it
Institutes of the Christian Religion by John Calvin (translated by Henry Beveridge) click Here to read it now. Click here to buy it.
Spiritual Man by Watchman Nee click Here to read it now. Click here to buy it now
The Two Babylons by Alexander Hyslop click Here to read it now.
Should Christians Fight by I. C. Wellcome click Here, here, or here to buy it (It was originally written around 1870, I don't think it is still in print, but it is the best book I have read on the subject.
Revolution in World Missions by K.P. Yohannan Click here to read it now or Click Here to get this book for free
Spiritism and the Fallen Angels by James M. Gray, D.D. (1920) Click here to read it now
The Manual of a Christian Knight [1501] by Desiderius Erasmus click here to read it now
The Knowledge Of The Holy by A. W. Tozer (1961) Click here to read it, or here to buy it.
How In This World Can I Be Holy (1974) By Erwin W. Lutzer click here to buy it or click here to buy it
And Probably Anything written by Martin Luther, Jonathon Edwards, John Knox, and other Protestant Reformation leaders.