Stephen Charnock's Discourses Upon the Existence and Attributes of God is a classic, but is over 500 pages. Daniel Chamberlin has done the church a service by summarizing the essential thoughts of Charnock on the doctrine of God for the 21st Century reader.
This is a great tool for groups to work through together, as each chapter is nicely divided up into bit size portions.Jeff has highly recommended it to me, and I look forward to reading it myself. Please let us know what you think here at the Reformed Baptist Blog after you've had a chance to read it yourselves. If you are interested in digging deeper into Charnock's work, you can get the free eBook of his Discourses Upon the Existence and Attributes of God here. I think you will quickly appreciate why an introductory, summary work such as A Portrait of God can be so helpful, especially if you are trying to acquaint others with such theology.