Bishiglomper
They usually only do circumcision on babies, before they remember it and they're all the way sensitive. And circumcision is usually a religion thing.
Fun fact: Male infants feel more pain in a circ than their adult counterparts for several reasons. First reason, male infants are not able to take oral pain killers (like advil, or even narcotic pain meds like vicoden).
Secondly, infants most likely experience MORE pain than an adult human.
Wiki on the matter
The present understanding of pain in babies is largely due to the recognition that the fetal and newborn unmyelinated nerve fibres are capable of relaying information, albeit slower than would be the case with myelinated fibres. At birth a baby has developed the neural pathways for nociception and for experiencing pain, but the pain responses are an immature version of that of an adult. There are a number of differences in both nerve structure and in the quality and extent of nerve response which are considered to be pertinent to understanding neonatal pain.[3][4]
The nerves of young babies respond more readily to noxious stimuli, with a lower threshold to stimulation, than those of adults. A baby's threshold for sensitisation is also substantially decreased, whilst the process involves a much larger area of sensitisation with each trauma.[5] The neural pathways that descend from the brain to the spinal cord are not well developed in the newborn, resulting in the ability of the central nervous system to inhibit nociception being more limited than in the adult.[6]
There are also indication that the neonate's nervous system may be much more active than that of an adult, in terms of transforming its connections and central nerve pathways in response to stimuli. The ongoing process of neural pathway development, involving both structural and chemical changes of the nervous system, have been shown to be affected by pain events, both in the short term and potentially into adult life.[5]
Wiki on the matter of pain and infants
Third the justification of "they won't remember it" is NOT logically sound. This leaves open the disturbing loophole that raping, or maiming an infant is okay because they won't remember it.
Also incorrect is your assumption circ is a religious thing. While it is partially a religious ceremony for some, most infant circ's in the US are for no purpose. They are elective, cosmetic and serve little to no medical function.
Also incorrect is your assumption they only preform circ's at birth. Hardly. Men, of age, have consented upon circ's all over the world.