REASONING ABOUT DESIGN
The Principle of Induction states that if something x has happened in certain particular circumstances n times in the past, we are justified in believing that the same circumstances will produce x on the (n+1)th occasion - David Foster Wallace
Religious belief is supposed to be about certainty, not probability. Jesus talked about faith moving mountains. The great saints and religious reformers didn't think that God "probably existed": they knew God existed. They staked their life on God and believed in him with total conviction. The Design Argument is irrelevant for religious faith.
Religious belief based on inductive reasoning is at the mercy of changes in scientific understanding. Look at the devastating effect Darwin's theory of evolution had on people's belief in God when On the Origin of Species was published in 1859! A religious belief based on inductive reasoning is built on very shaky foundations..
The Design Argument leaves room for doubt, which is important for reasonable faith. Only fanatics and bigots believe with total certainty. Reasonable people have doubts about things. The Design Argument reassures believers that their faith is reasonable but it leaves a place for questioning and mystery in life.
Inductive reasoning is good for religious belief as it inspires religious people to take an interest in science to support their beliefs rather than dismiss science. Scientific discoveries that show design in nature strengthen the Design Argument. For example, Michael Behe points out that the bacterial flagellum doesn't look like it could have evolved by chance (he claims it is "irreducibly complex").
without the influence of custom we would be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses - David Hume