Interesting that no one thought as much about any of the other excuses as the religion excuse.
Personally, I don't really get how people can be so fiercely loyal to the "entity" who:
Put the tempting tree, and the "serpent", in the garden, then punished his prized creations because he made them too weak to resist...
Praised one scarifice (animal), snubbed another sacrifice (grain), causing (and allowing) the snubbed sibling to murder his brother - then cast the murderer out of paradise and punished him and seven generations (!

of his children for the sin he was tempted to commit... talk about holding a grudge... what is good and wise and just about holding a man accountable for a transgression committed by his great-great-great-great grandfather?
Required Abraham to put his son on the altar, slash his throat, and toast him; the one instance where god "changed his mind" (keeping in mind the all-knowing and unchangeable nature of god...)
Required all his devotees to chop off a part of every male's sex organ...
Beset one of his most devoted worshippers with plague after plague after plague, eventually killing off all his herds and crops, then all his beloved children, all to settle a silly bet with god's rival. (I guess the story has a good ending, god "replaced" Job's children; I'm sure anyone reading this who has ever lost a child knows that they are easily replaced.)
Raped a poor virgin girl, with the sole intent of impregnating her, knowing full well that her (his) son would eventually be tortured and murdered...
I'm sure that I have left out a few. Does anyone else see a pattern here? I just can't figure out why anyone would continue to call this a loving, giving, all-knowing, just, merciful god - and continue to mutilate children with the excuse that it is a covenant with god. Circumcision, for religious reasons, just does not make sense to me.
As for just simply automatically doing it at birth, I say if you want to slice off pieces of your baby, leave his cock alone and maybe cut off one of his ears, or a toe or something.