Show them no mercy (Zondervan, 2003) edited by Stanley N. Gundry is a collection of four essays dealing with the problem of God’s violence in the Old Testament. The first is thoroughly unbiblical, but the other three are good summaries of the ways evangelicals wrestle with the issues. Two fuller length and very good books on the same issue are Tremper Longman’s God is a Warrior (Zondervan, 1995) which is very strong biblically and theologically, and Paul Copan’s Is God a Moral Monster? (Baker, 2011) which is easier to read and also tries to deal with other socially relevant issues such as slavery and attitudes to women. This last book is the only one of the three that could be useful to give to non-Christians, but only if they have a real interest in, and knowledge of the Bible.
The subject of hell is not one that seems to encourage many good books. John Blanchard’s Whatever happened to hell? is among the most useful (Evangelical Press, 2003). Dick Dowsett’s God, that’s not fair! (OMF, 1982) is very easy to read, and still helpful. Both are to designed to help Christians.