Tattoos and Piercings

I know this doesn't have much to do with Psalm 18, however, me and my friend were talking today about how in Judaism it's against "Jewish law" to pierce and tattoo ones body.  People with tattoos and piercings are not allowed to be burried in a Jewish cemetery.  I find this interesting that not getting tattoos or piercing is a test of faith, and respect for religion.  How is personal appearance a test of faith?  Me and my friend then got to talking about how Rabinical law should be adjusted to suite the times.  It's a new day in age, and tattoos and piercings are seen as less taboo then they used to.  I also then got to thinking about the idea that religions can be adapated. 

I think I said this in one of my other blogs too, but i've always been under the impression that religions are set in stone, or that the underlying beliefs that come from religion are set in stone. Because this isn't the case it makes me feel like religion is less solid then i've previously viewed it.  It makes me believe in it less.  So what is religion really?  Is it just something to believe in  to make life seem more interesting?  Is it just something to guide us so we don't feel lost? ...