One thing that is getting lost in such debates is epistemology. Epistemology is concerned with the nature and scope (limitations) of knowledge. It addresses the questions: What is knowledge? How is knowledge acquired? How do we know what we know?
In a short book (really more of a long essay) Lesslie Newbigin has written about how we set out to know things and what the limits of our knowledge might be. There are helpful distinctions between "cause" and "purpose." Many of the debaters of our time would do well to consider these words from Newbigin.
Cause is something that can be discovered by observation and reason. Purpose is not available for inspection because, until the purpose has been realized, it is hidden in the mind of the one whose purpose it is. Suppose that going along a street, we observe men at work with piles of bricks and bags of cement, and we guess that a building is being erected. What is it to be? An office? A house? A chapel? There are only two ways to discover the answer: we can wait around until the work is complete and inspection enables us to discover what it is. If we cannot wait until then, we must ask the architect, and we will have to take his word for it. If the work in question is not the building of a house but the creation and consummation of the cosmos, the first alternative is not available to us. We shall not be present to examine the end product of cosmic history. If the whole thing has any purpose (and of course we may decide, as postmoderns do, that it has no purpose), the only way we can know that purpose is by a disclosure from the one whose purpose it is, a disclosure which we would have to take on trust. There is no escape from this necessity. The modern antithesis of observation and reason on the one hand versus revelation and faith on the other is only tenable on the basis of a prior decision that the whole cosmic and human history has no purpose and therefore no meaning. It is possible to make this assumption, but it is not necessary. The question whether the cosmos and human life within it have any purpose other than the individual purposes we seek to impose on things is one that cannot be decided by observation. If we live with a prior assumption that human life has no purpose; then we shall act accordingly, and there will be no possibility whatsoever of discovering its purpose.*Is Newbigin right? Have we assumed that the universe is without purpose? If the cosmos and human life within it have a purpose, how would we know that purpose? Does an assumption of a purposeless cosmos affect the way we approach life in this century? Newbigin affirms that indeed there is a purpose and the architect of the cosmos has revealed to us the purpose. We must take it on trust with "proper confidence" and "personal knowledge." The rest of the essay expands upon these themes.
*Newbigin, L. (1995). Proper Confidence: Faith, Doubt, and Certainty in Christian Discipleship. Grand Rapids: Wm. B. Eerdmans Publishing Co., p. 57, 58.