I think you are right not to consent to a circumcision, and your husband won't be mad at you for your whole life. Anyway, it's not about your DH's feelings, it is about your son's feelings.
Penises are private, your son will not be made fun of. Well, all kids get made fun of, but it's not about their privates. Be strong and don't be bullied into doing a circ.
You don't need to convince your DH If anything, just try to get him to see that being intact is OK. Most of the world is uncirced, and fine. Let him know that your son will be perfectly healthy and happy and there's no reason to circ.
Be confident and be a leader about this. Your dh doesn't have to talk about it, if he doesn't want to talk, that's OK. Be open to hearing his feelings, but don't cave in and allow a circ. It's OK for your husband to have feelings and fears about your son getting teased, but just reassure him it's all going to be just fine.