If you assert that you believe in something you're absolving yourself from being challenged for evidence.

Not at all, Steve. For example, I believe I truly am the natural-born son of the married couple by whom I was raised and whom I regarded as my parents. If necessary I could refer to my birth certificate in support of this belief, and would not object to a DNA test.

The evidence behind my religious beliefs is circumstantial and subjective, but it exists.