D’Sousa is using classical Christian apologetics in his book, and I would encourage more Christians to explore this approach. Reason can only take you so far, but it can certainly point someone in the right direction. Flew is a prime example of the limits of reason. At some point the Holy Spirit has to create faith. There is a growing militant atheistic movement in our culture, and apologetics is a good way to confront it. No one is going to convince a dogmatic atheist that God exists, but you can influence someone that is open to the idea.
Regards,
John