We're a non-circing Jewish family (conservative). I am pregnant now, and we don't know the gender of our baby that is due in July. At first, dh wanted to circ our baby if it turns out to be a boy, but we had some really good conversations about it. For us, it really started with the knowledge that no subject was off limits. Neither of us ever gets to say, "I'm doing this to/with our child, and any discussion about it is off limits". We both respect each other enough to hold a conversation about anything, and really listen to what the other has to say about it.
We aren't the sort of people who do things just because someone says so (I guess, even if that someone is god). Everything needs to have a good reason that we reach through research and the well-being of our children at heart. We don't vax either, and we didn't reach that decision lightly.
I sat dh down and told him that we needed to talk about this, and start from a neutral place. We would weigh all of the information that we could find, and make a decision from there.
Although we are conservative Jews, we don't follow every rule mandated to us. We don't keep kosher, we don't strictly observe the sabbath, etc. Although we do believe in our religion, we do pick and choose some of what we choose to follow, because of how it fits with our beliefs and lives. Permanently removing a major piece of our son's organs, just because the bible says to, was not an option.
I don't know much about the Muslim religion, but I can say that the Jewish religion has come quite a long way with making men and women more equal, even when not allowed by Jewish law. Women are now given the right to end a marriage, Jewish girls have a bat mitzvah, etc. What if in an effort to equalize males and females, rabbis now started mandating female circumcision? Everyone would be up at arms. Maybe this is a time that the males should be given the same right to bodily integrity as females. The right to make decisions regarding their own bodies, and the right to make that covenant for themselves, if they so choose.
Modern Jews also do not follow all of the mandates of our religion, but find ways to symbolize our observance of rules. For instance, on Passover, we no longer sacrifice an animal, but have a roasted shank bone on our seder plate. Why not find a humane way to symbolize this covenant without cutting off a part of our son's body? Slowly, this concept is catching on with Jews, and I am proud to be a part of the group that is asking questions and making our rabbi think about it.
I don't know how much of this applies to how your dh follows his religion or if any of this speaks to modern Muslims, but maybe it will give you a place to start.