The Bible in a modern version preferably the New International Version which is probably the most accurate. (use a chapter a week) This is the best house book resource and add to that a good commentary.
"Mere Christianity" - C. S. Lewis
"Basic Christianity" - John Stott
"Jesus Among other gods" - Ravi Zacharias
"More than a Carpenter" - Josh McDowell
"The Wonderful Spirit-Filled Life" - Charles Stanley
"Questions of Life" and "Challenging Lifestyle" - Nicky Gumbel