J.I. Packer said of Richard Baxter's A Christian Directory that next to the Bible it was:
...the greatest Christian book ever written.
Jonathan Edwards said of Petrus van Mastricht's Theoretico-Practica Theologia that it was:
...much better than Turretine or any other book in the world, excepting the Bible, in my opinion.
Thomas Hooker and Increase Mather said that William Ames' The Marrow of Theology was:
...the most important book beyond the Bible for making a sound theologian.
Charles Spurgeon said of Matthew Poole's English commentary:
If I must have only one commentary, and had read Matthew Henry as I have, I do not know but what I should choose Poole.
Samuel Rogers said of his father Daniel Rogers' Treatise on the Two Sacraments that he
could misse any booke lesse except [the] bible.
Samuel Johnson, a student at Harvard, once said of Johannes Wollebius's The Abridgement of Christian Divinitie that at Harvard it was
considered with equal or greater veneration than the Bible itself.
R.C. Sproul said:
Pelagianism has a death grip on the modern church. Perhaps the most important refutation of this distinctive is [Jonathan] Edwards' Freedom of the Will. I believe this is the most important theological book ever published in America.
James Hervey said of Walter Marshall's The Gospel Mystery of Sanctification that if he were banished to a desert island and could take only a Bible and two other books, Marshall's classic would be among them.
According to Philip Schaff:
The moderate and judicious Richard Baxter esteemed the Westminster Confession and Catechisms the best books in his library next to the Bible...
In response to the question, "If you were stranded on a desert island, and could only have one book with beside the Bible, which book would you choose?" Dr. Joel Beeke said:
Without a doubt, Wilhelmus a Brakel's The Christian's Reasonable Service -- and not just because I would be getting four volumes for one!
Martin Luther said of Philip Melanchthon's Loci Communes Theologici:
Next to Holy Scripture, there is no better book.
If I might read only one book beside the Bible, I would choose [William Gurnall's] The Christian in Complete Armour.