"It is one thing to say that science is only equipped to test for natural causes and cannot speak to any others. It is quite another to insist that science proves that no other causes could possibly exist. . . . There would be no experimental model for testing the statement: 'No supernatural cause for any natural phenomenon is possible.' It is therefore a philosophical presupposition and not a scientific finding."
In other words, you can not in one swing say that science only tests natural causes and in another conclude that this means no supernatural causes exist. It would be like taking a metal detector to the beach and stating that there are no non-metallic substances on the beach based solely on the fact that you are unable to detect them with your instrument.