No argument is truly irreducibly secular. For anyone who wants to make an argument about anything beyond procedure will have to deal with questions of meaning, morality, and value--questions that are larger than any individual human frame of reference. On issues like those, there are no arguments that are genuinely secular. As a matter of fact, listen carefully to those who most seek to advocate purely secular arguments. On questions of meaning and morality, their arguments are themselves just as essentially religious as the "religious" arguments they reject. They may believe their claims are not religious, but they end up being religious precisely because they are anti-religious. Moreover, they attempt to set up their own version of God--their own idea of what is the ultimate good--in order to determine value.This point, which I applied to the current debate over the ethics of embryonic stem cell research, must be hammered home again and again in the public square. How I wish more Christians who have opportunities to discuss matters of public policy in the media would stress this point and press their opponents on it. For that matter, I wish all Christians, regardless of their access to media platforms, would be adequately prepared to make this case. In order for this to happen, however, we must view worldview formation and analysis as a vital part of the church's disciple-making task. Unless we teach believers how to think in wholes and recognize how individual beliefs emanate from larger systems of thought, they will be less equipped to "destroy arguments and every lofty opinion raised against the knowledge of God" (2 Cor. 10:4-5).
....There is no neutrality. On questions as ultimate as the existence or non-existence of God, or the binding or non-binding character of His dictates and commands, or the objectivity or subjectivity of morality, or the absoluteness or non-absoluteness of truth, there are no mediating positions. There is no neutrality.
Nancy Pearcey's Total Truth is an excellent resource for understanding worldviews in general and the Christian worldview in particular. Pearcey was a student of Francis Schaeffer's and is doing a marvelous job of exposing a new generation to the relevance of his thought to the contemporary intellectual, political, and social scene. You can listen to an interview with her about the book at Pensees: Faith Seeking Understanding.