When an adult man converts to Judaism, does he need to be circumcised? If he isn’t, does he need to get circumcised?
Unsurprisingly, this is a rather important topic to a lot of male converts to Judaism, and a lot has been written about it.
Short answer: No to your first question, yes to your second. In conversion to Judaism, even a previously circumcised non-Jewish man is supposed to undergo a mostly symbolic circumcision drawing a single drop of blood, and an uncircumcised man is supposed to have the foreskin removed. Ritual immersion is also part of the conversion process.
Not every modern Jewish authority or Jewish congregation considers circumcision strictly necessary for converts (there are some in some places who don’t even mandate it for Jewish-born boy babies), and of course there are exceptions made for health issues. But the vast majority of halakhic opinion is that yup, that’s the rule.
Ok, thanks.
When my then-husband (circumcised) converted 30 years ago, this was not a requirement, nor even a suggestion. It was a middle-of-the-road Reform synagogue. Evidently, the rabbi has plenty of leeway.
Significantly more leeway than the mohel would have, I would think 
I know a certified mohel who is also an MD. He is Reform, and not as experienced [READ: fast] as the Orthodox mohel, who does pretty much every baby bris in the entire state of Indiana-- including my son’s. Anyway, this guy who is an MD-- his specialty is uncircumcised men who want to convert. He uses a local, plus the same gas that dentists use, if requested, prescribes 3 days of prophylactic antibiotics, and schedules a 1-week follow-up. He has men travel in from a 4-state area (Indiana, Ohio, Kentucky, and Illinois), and probably does 12 a year. They are slower than the Orthodox mohel, but with a local and gas, it doesn’t matter. And having sat through my son’s, it feels really long at first, especially when they take your newborn out of your arms, but then, suddenly, it’s over. He wasn’t even crying when I got him back-- thanks to that drop of wine.
I heard the two mohels once collaborated on a baby with some (minor) health problems. The mohel actually did the bris, but the MD was right there on stand-by, and prescribed antibiotics. I’m not sure exactly what the issue was, but I know the mother was diabetic, and the baby had been premature. The baby was actually about 3 months old at the time of the bris, not 8 days.
I know so much, because I had the MD’s daughter in my religious school class right at the time when he was undergoing his mohel training. And I had a friend who converted, and went to him for his bris. Since it’s technically a simcha, a few of us went with him, but we waited outside. And we stayed with him for the 4 hours he wasn’t supposed to be alone after the gas.
Circumcision always struck me as a pretty hard-core sign of membership in a group, as in someone choosing to do it is likely serious. It is not unique to Judaism. Some groups practice even more extreme body modification, like penile subincision.
There is a striking passage in the book of Exodus where God seeks to kill Moses, and leaves him be after Zipporah circumcises their son.