Connecticut has just become the 6th state to end religious exemptions for childhood vaccination. Medical exemptions, of course, are still allowed. Note that the law does not require parents to vaccinate their children, but it does require that children receive a specified schedule of vaccinations in order to attend public school.
I can understand why this is a difficult issue for liberals, in the post-FDR sense of the word. Speaking only for myself here, while I personally do my best to be guided by science and reason, I see freedom of belief as an inherent value -- not an absolute, value, of course, because liberty interests are always in conflict and every case is a balancing act. But a value nevertheless. I respect the First Amendment on this.
But of course, religious belief does not in general exempt people from the secular law. If your religion demands human sacrifice, you don't get to practice it. If your religion demands that other people not be allowed to practice theirs -- assuming no human sacrifice or other violations of the secular law are involved -- you don't get your way. Adults can choose to harm themselves for religious reasons, as for example by refusing medical procedures or following an unhealthy diet. However, there is plenty of case law that says they can't refuse life saving treatment for their children, or starve them, or torture or imprison them, because they think Jesus wants them to do it.
In the case of childhood vaccination, people who claim religious exemption aren't just harming their own children, the are endangering others who cannot be vaccinated, or for whom vaccination is ineffective, for legitimate medical reasons. So this falls very close to, if not within, the human sacrifice moral category. I also have to say that I doubt that most people who want to claim this exemption really do have any religious objection, it's just an excuse. The only religion with a substantial number of followers that has an actual objection to vaccination, as far as I know offhand, is Christian Science. Most of these people have just made up their own religious beliefs, for the occasion. What's actually going on is that they have false factual beliefs.
So on reflection, I support this legislation. Happy to hear other opinions, but any based on factually false assertions about vaccination will not be entertained.