It’s not just that the ACLU supports the right of child molestors to have a fair trial or have the right to not self incriminate or anything like that. Those rights are not in dispute. There’s no serious movment against child molestors having those rights.
The problem is that the ACLU has been very supportive of NAMBLA, which is a criminal organization. NAMBLA gives instructions to child molestors on how to abuse and not get caught. This is criminal activity, not speech that deserves protection. For the ACLU to defend this is absurd and washes away any credibility they might have had.
Further, the ACLU’s anti-gun and anti-religion stances rub a lot of people the wrong way. It sucks, because I like the idea of an organization that protects civil liberties. I’d love to be a member of such an organization. But, as is typical with such groups, they have been hijacked by extremists with radical agendas IMO. As such, I cannot support them.