"A1: If there is no Jesus, why are there churches?"
Answer: Churches exist because people believe that there is a Jesus. But people who believe that there is a Jesus is not a proof that there is a Jesus.
Due to popular demand... I edit:
You say :
"The presented statement seems to assume that:
A2: If there is Jesus, it follows that there are churches."
While I agree I prefer to translate the A1 question with this statement:
A2-alternative: If there are churches, it follows that there is Jesus."
I see it just an obvious wrong assumption. I choose to transpose the logic part of this sentence to a simpler, more obvious model for easier comprehension:
"If children writes letters to Santa (If there are churches), it follows that there is Santa (Jesus)."
And here I can be wrong but I don't feel the need of an "adlatina" sentence to describe it.
But... What's make the question interesting is not the logical part of the fallacy.
In this sentence there is a very pragmatic part.
It does work on peoples.
Such an argument could definitely be accepted and even firmly defended with billions of logical fallacies by a deeply religious person!
I think the logic of the question is evaluated only because there is "Jesus". Without beliefs (religious, political, etc...) the logical part is naked. What's disturbofascinating is the idea that still, it could easily work with some believers.