I'm Jewish and we circumcised our son. My view is pretty clear: of course it's a bloody and primitive act -- my religion was born in the desert to a nomadic tribe thousands of years ago. The ensuing generations have softened its many of its harsher measures and created the most enormous and sophisticated intellectual edifice on top of the original concepts, but Judaism is still an ancient thing that does not fit very well with the modern world.
However. It is also a precious gift. Di goldene keyt, the "golden chain" connecting each generation to the previous generation through a shared history, extraordinary ideas, and a still-revolutionary way of thinking about the world is at the heart of my identity. Putting it on hold until my son is 18 would itself be to act at odds with the tradition, as would picking and choosing which bits to transmit.
My sincerest hope for my son is that it is the most bloody act of barbarism he ever has to endure. Many, many generations of his forebears were not lucky enough for that to be true.
I realise that all of this will be completely unsatisfactory to people with a strong anti-circumcision view. I say it to explain, not to justify. And like MumNWLondon, I feel a strong sense of obligation to get the bris done and would have gone abroad to make it happen if the law changed.
The tricky thing is, prism, that Jews have historically been forbidden by secular law from many aspects of religious practice: keeping kosher, keeping Shabbat, fasting on Yom Kippur, wearing a skull cap (men) or head covering (women), etc etc. So we've got that historical context playing in our heads when people talk about banning our religious practices, despite the context being modern concerns about child protection and human rights rather than state-sponsored persecution.