Christian metal is a cross-genre term used to describe metal bands that introduce Christian themes into their lyrics. This sub-genre has a long tradition within metal, starting with Christian hard rock bands springing up alongside the NWOBHM phenomenon to the Christian metalcore bands today. Often the Christian themes are melded with the subjects of the genre the band is rooted in, generally providing a Christian take on the subject matter. Examples include Stryper, P.O.D., Tourniquet, and Mortification.