The battle does not have to be fought in the secular unversities. The individual Church's and their universities must develop philosophical arguments to counter deconstructionism, existentialism, structuralism, post modernism, feminism, post colonialism et al.
Christians can and must do fight the battle or else suffer continued marginalization.
I don't agree with your premise that Christianity and philosophy are incompatible. Wasn't Augustine a neo Platonist? Wasn't Aquinas an Aristotilian?
I didn't say Christianity and philosophy (as mode of thinking) are incompatible, rather that serious philosophers today simply do not speak in the language of Christian theology and would not take arguments couched in Christian terms seriously. Even those philosphers who still read Augustine and Aquinas usually prefer Plato and Aristotle.
Part of the problem is that ultimately, acceptance of Christianity rests on some sort of arument like Origen's credo absurdam est, an argument to faith transcending rational argument. Unfortunately, from a philosophical point of view, all of the attempts to make rational arguments for the existence of God, ala Aquinas, Scheler and countless others, or even rational arguments for belief regardless of whether or not He exists, e.g. Pascal's bet, have been largely viewed as unsuccessful. Hence, philosophers have written off the question as unknowable -- which allows some to be Christians (or Jews) some to be deists, others agnostic and still others athiest. Any attempt to argue from a seriously Christian perspective would be met with the argument that the premise was not subject to validation and hence not worth discussing.
BTW, the fact that I think Christian arguments will not get anywhere in the philosophy departments does not mean I am not a Christian (which I am) or that I think Christians should not be active on campus. I think they need to focus on spiritual matters more directly and less on the philosophical. I think Christains need to re-examine their hostility to the entire Enlightenment enterprise and work within those parts that are not incompatible with a Christian perspective on matters spiritual. My own view is that the English tradition is (and this may account for some of the persistence of Christianity in the US) not incompatible with Christianity, as long as one does not insist on Bible inerrancy which precludes science. Most philosophers will not object to arguments by Christians per se (as they regard the matter as unknowable), just arguments couched in Christian terms. Christians who wish to win need to understand this and modify the way they approach matters accordingly.