A robust natural theology may well be necessary for the gospel to be effectively heard in Western society today….
Properly understanding our culture is important because the gospel is never heard in isolation. It is always heard against the background of the current cultural milieu. A person raised in a cultural milieu in which Christianity is still seen as an intellectually viable option will display an openness to the gospel. But you may as well tell the secularist to believe in fairies or leprechauns as in Jesus Christ!…
It is the broader task of Christian apologetics, including natural theology, to help create and sustain a cultural milieu in which the gospel can be heard as an intellectually viable option for thinking men and women. It thereby gives people the intellectual permission to believe when their hearts are moved.
— William Lane Craig, from God Is Not Dead Yet, http://www.christianitytoday.com/ct/2008/july/13.22.html