Naturalism constrains the interpretation of scientific findings because it cannot allow that any data might point beyond the natural world to a transcendent (or supernatural) cause since it denies that any such cause is possible. As the eminent philosopher, Prof Alvin Plantinga points out, ‘Naturalism is the idea that there is no such person as God or anything like God; we might think of it as high-octane atheism or perhaps atheism-plus. It is possible to be an atheist without rising to the lofty heights (or descending to the murky depths) of naturalism. Aristotle, the ancient Stoics, and Hegel (in at least certain stages) could properly claim to be atheists, but they couldn't properly claim to be naturalists: each endorses something (Aristotle's Prime Mover, the Stoics' Nous, Hegel's Absolute) no self-respecting naturalist could tolerate.’ 
If science is a search for truth, it should be open to all credible explanations. Natural processes may explain many phenomena, but to say that they must explain everything, especially in the area of origins, is a dogma arising from the controversial philosophical assumption of naturalism rather than a necessary consequence of empirical scientific activity.
 Cited from Professor Alvin Plantinga, Evolution vs. Naturalism: Why they are like oil and water. http://www.booksandculture.com/articles/2008/julaug/11.37.html