The Death of Death In the Death of Jesus Christ, by John Owen
This is my favorite book. It is the most significant work on the atonement of Jesus Christ in print. It is not for the faint of heart or the casual reader. It is work. And worth the effort.
Freedom of the Will, by Jonathan Edwards
This classic work is an essential read for understanding how free will harmonizes with the sovereignty of God.
Shepherding a Child's Heart, by Tedd Tripp
This is the best book on raising children in print. If I could require one book be read by everyone in our culture, this would be the one. It's also available on video.