I would probably advise against arming yourself with more arguments to go against anything he tries to say just because sometimes in situations like this, people just want to feel heard. It it not always about 'winning' an argument, sometimes it is about feeling respected enough that your partner would stop and actually listen to what you are saying and feeling validated. It also makes the other person more likely to listen. Sometimes once people have had themselves heard, they don't feel the need to keep debating it and they realise it wasn't as important. I think by making arguments for every reason he gives, it may just make him feel not listened to and more determined. It is not guaranteed that he won't decide it is important, but at least he will feel heard and tell him you would like to think about it for a couple of days and don't discuss it. In a couple of days, if you come back to talk to him and just say that you have a couple of concerns about circumcision and your reasons, hopefully he will listen also.

Also, be careful about the info that you gather because not all of it is entirely correct for Australia and if you want to argue from an info point of view, if you information isn't correct then it could cause more issues and further push your DH into wanting circumcision at all costs.

I am not trying to give an opinion either way on circumcision because what happens in your family is totally up to you and your DH. I really think the important thing here is that you listen to each other and not necessarily armour up for a debate. Everybody likes to feel like their opinions are valid and respected especially in a relationship. I think it is important you understand your own point of view and why it is important to you so that you can share that with your DH as well but not to argue with everything he says, just so that you can share your own opinion.

I hope all that makes sense ...