Fideism plays an important role in some sects of Christianity, but is considered heresy in others.  It is not mentioned in any of the eccumenical creeds.<p>That being said, there has always been a strong minority pushing for it, and one interpretation of the doctrine &quot;Sola Scriptura&quot; (which <i>is</i> a core tenent of Protestantism) would be that anything contrary to scripture is wrong (hence young-earth creationism).