Two of my closest friends take the view that you should not smack your children. As I was looking through the table of contents to Andreas Kostenberger's book God, Marriage and Family I noticed that he has a section on 'Physical discipline.'
Kostenberger points to the 'rod' mentioned in the book of Proverbs (e.g. He who spares the rod hates his son, but he who loves him is careful to discipline him, 13:24 see also 22:15; 23:13-14; 29:15). After briefly outlining some of the objections to spanking he writes
Should parents exercise physical discipline? The modern criticisms against spanking typically employ overstatement and inflammatory rhetoric. Appealing to excessive cases that involve abuse does not justify abandoning spanking as a form of discipline. Children need to learn the consequences of wrong behaviour, and spanking can be a useful means to convey that lesson. However, parents should take child's unique personality and temperament into account and be aware that some children may respond better to alternative forms of positive or negative consequences and reinforcement (i.e., timeouts, rewards, loss of privileges).