The book I am currently reading is quite interesting. It is called "Echoes of Eden" by A.W. Tozer, and it deals with how God has constantly been calling out to sinful mankind to return to Him, ever since He called out to Adam after he and Eve sinned in the Garden of Eden and hid from God's presence (hence the name of the book). Tozer points out the many diverse ways in which God unceasingly calls out to us (conscience, nature, Scripture, and the Holy Spirit).
"There is a divine voice that continues to call. It is the voice of the Creator, God, and it is entreating them. Just as the shepherd went everywhere searching for his sheep, just as the woman in the parable went everywhere searching for her coin, so there is a divine search with many variations of the voice that entreats us, calling us back."
- A.W. Tozer, Echoes From Eden, Chapter 1