Listen here to a comprehensive interview on NZ's Radio Rhema with Mark J. Keown, author of the Book What's God Up To On Planet Earth: A No-Strings Attached Explanation of the Christian Message: http://www.rhema.co.nz/index.php?option=com_content&view=article&id=10083:one-2-one-chuck-missler-and-difficult-questions&catid=86:one-2-one&Itemid=430
The book explains the Christian message to unbelievers clearly and based around an easy to remember structure of five R's: Relationship, Rupture, Restoration, Return, and Response. It is also a very useful tool for discipleship of young Christians. For those who want to be better equipped for evangelism, it is a very helpful resource. It is not too heavy, but gives a compelling vision of what God is up to in this world.
The book can be purchased in NZ from Castle Publishing: http://www.castlepublishing.co.nz/whats-God-up-to-on-planet-earth.html. Or, you can request the book from a NZ Christian book shop like Manna.
The book can be purchased from Koorong in Australia: http://www.koorong.com.au/search/product/view.jhtml?code=9780986462108.
The book has just been published and about to be released in the US: (https://wipfandstock.com/store/What_Gods_Up_To_on_Planet_Earth_A_NoStringsAttached_Explanation_of_the_Christian_Message).
It can be purchased internationally from Amazon Books: http://www.amazon.com/Whats-God-Planet-Earth-explanation/dp/0986462101.