My response would be to tell them what the following terms mean…
Ad Hominem attacks.
Reducio Ad Absurdum and
What it means to Strawman a argument.
These are just some of the things wrong with such attacks.
I’m reminded of what my Mother told me when I was trying to become a prefect.
You will catch more bees with honey than with vinegar.
Reductio ad absurdum is actually not a logical fallacy. It’s a logically valid means by which to disprove a deductive argument by taking its implications to a conclusion which is found to be absurd by both parties.
Most of the examples given by the OP are not
reductios, rather straw men. I’ve never heard a Christian theologian profess belief in a “Jewish zombie” or proclaim to practice “cannibalism” through the Eucharist. These are just juvenile caricatures of Christianity which are easy to knock down, and thus give these particular atheists something to feel satisfied about.
Edit: Technically speaking, these aren’t even arguments. They’re just statements, so it’s probably not even proper to call them straw men since they’re just rants.
A true straw man
argument would be something along the lines of:
P1: The Bible says to stone your children,
P2: Christians believe every word of the Bible,
C: Therefore, Christian faith necessitates the stoning of children.
To show that I’m not being impartial: another straw man would be:
P1: Evolution teaches that men come from monkeys.
P2: If men came from monkeys, there wouldn’t be any more monkeys.
P3: There are still monkeys,
C: Therefore, evolution is false.
I haven’t seen a true
reductio ad absurdum against a tenet of Christianity, but something that comes close, at least with regards to theism in general, would be Epicurus’ Logical Problem of Evil.