I don't know if this is helpful, but I am reading The Reason for God and find it very thought provoking. I have not read the other book by D'Souza. Tim Keller is a very gifted theologian and has a real heart for all people. There is a website for the book, www.thereasonforGod.com that may answer more of your questions.
I have read both books and was pleased with them both. The Keller book is more concise and a quicker read, and in my humble opinion, more elegant, more beautiful, just as well reasoned and yet less technical. Both will equip the reader to answer skeptics. the Keller book gave my own faith a huge lift and brought me closer to God; clarified for me several theological points...especially helped me appreciate the trinity in a new way.