First, sorry for double post but I have a horrible memory, get sidetracked very easily (gr ftw)
Anyways, I would say that it's mainly aesthetic (firefox spell check, yay!). Mainly it's for keeping it clean but if you can pull it back then it's pretty useless. Religion - Jews beside, I can't think of a religion which would necessitate circumcision.
My advice - don't. It makes you feel like you're gonna spontaneously mess your pants when you walk. Also your dick will sting when you piss. It's not too fantastic. Plus, au naturel.
If you think that you need to lop off the end of your kid's dick (note connotations) to keep the dick cheese at bay, no one can stop you.
I miss my foreskin. :'(