I highly recommend the divine, matchless and indispensable Holy Bible.

The Bible is the inspired, infallible, unchanging and all-sufficient Word of God. Study it, cherish it, abide in the Word, stand on the Word, live by the Word through the power of the Spirit of God.

All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work.
2 Timothy 3:16-17

The Mystery of History
Linda Lacour Hobar

For children:

A Pilgrim's Progress
John Bunyan, retold by Geraldine McCaughrean

The Holy War
John Bunyan

Shepherding a Child's Heart
Tedd Tripp

Leading Little Ones to God
Marian M Schoolland

Jesus ABC
Patricia Newman

For adults:

Fox's Book of Martyrs

The Crucified Life
A. W. Tozer

The Pursuit of God
A. W. Tozer

The Valley of Vision
Edited by Arthur Bennett

The Attributes of God Vol. 1
A. W. Tozer

The Attributes of God Vol. 2
A. W. Tozer

Why Revival Tarries
Leonhard Ravenhill

The Kneeling Christian
An Unknown Christian