Os Hillman has written nearly a dozen books and is considered the grandfather or founder of the Marketplace Ministries movement in the USA beginning in 1997. His daily devotional "Today God is First" (TGIF) is read by 200,000 of people with his writings and studies of how the word of God applies in the marketplace in both business and ministry, areas seldom discussed in churches or by pastors.

Os had a very successful advertising agency for many years in Atlanta until he faced many "big crisis" he could not overcome in his own strength, which became a tool for the Lord to get Os' full attention.

The Power of the Staff draws the parallel from the staff that God put in Moses hands which became his understanding in the work and calling he was to undertake. He describes 4 types of Christians in the marketplace.

http://www.marketplaceleaders.org/tgif/