Mohler has an essay on this topic.
One reason that Christian intellectuals are fading out is that in an avowedly 'secular' world, and largely post-marxist academy (or its fellow travellers), Christian discourse is ruled out of court.
But it goes further; we fail to pin the non-Christian world on the horns of its own dilemma that comes from world views that fail to make sense of the worlds as we really live in it: materialism...romanticism (I mean things like nature worship)...panentheism (even if vaguely held). Much Christian discourse seeks to appease rather than challenge.
A great example of this poor practice is a Q&A (ABC TV leftist political platform) exchange between John Dickson, a Sydney Anglican minister, and presumably evangelical, and a humanist/materialist, where John agreed with the other's cosmogony, unwittingly making God something within the universe, and dependent; instead of challenging him on the epistemological thin ice he could not avoid being on, as a materialist.
There's also this essay.