“This is so common I probably don't need to give one, but a great example was the constitutional amendment last year to ban gay marriage in California. What a stupid, pointless, hateful thing to do. And all because of these "ridiculous/irrational" beliefs. Don't seem so harmless now, do they?”
What is marriage more than a label? Would there be a difference between rights of people who have a marriage or who have a civil union? In some countries the government does not know (and does not care) who marries or civil unions who.
I suspect this debate has two sides – Christians who want to “protect” marriage and gays who want to “force” acceptance. Preferably the state should declare everything as civil unions.
“However, making such points is kind of useless. We have no way to know how many hospitals would be in Africa absent the CC.”
The point is exactly that the CC is the highest non-governmental donor of aid. You can criticise than, but per person the Catholic church gives more aid than most secular and humanist NGOs.
“Doesn't make their Interdimensional Space God any more findable,”
It is not about the findability of their god. It is what happens here and now – and Catholics are pretty positive influence.
“and their attitudes towards eg. Third World contraception remain utterly comtemptible.”
This again is debatable. The CC has had huge influence in the AIDS programs of Uganda and it is one of the few countries that reduced its HIV prevalence rate (with an ABC program). I live in a country that places a strong influence on contraception (South Africa) and AIDS ravages at a prevalence rate that is more than 20%.
“Once you accept that taking orders from imaginary friends - or their supposed representatives on earth - is OK and valid, how can you argue when those orders swing to an activity you don't agree with?”
Or if someone tells you to make peace? Religion has both positive and negative influences – just like any other ideology (e.g. communism). Religious people were fairly well persecuted in the name of state Atheism (e.g. ex-Soviet Union, China).
“it makes it very difficult to reject later on when the activities of the "faithful" turn counter to what you know to be the best interests of society and humanity. “
As I said, everyone has irrational beliefs (e.g. Humanism). Your moral basis is probably built on several irrational beliefs.