Nearly all of us have specific religions we think are ridiculous. Do you think Scientology is ridiculous? What about some of the demonstrably false beliefs of the Mormons? What about the amusing beliefs of some of the isolated island cultures who have worked their experiences with more advanced people into their theology? What about the people who thought their saviors were coming with that comet, oh about 10 or 15 years ago? Even if you are so tolerant of ridiculous methods for evaluating truth that you personally don't contemplate how ridiculous at least some beliefs are, the vast majority of us are not so generous.
When Mormonism encompassed only a few thousand people, no one thought it was unfair to consider them ridiculous. Only after they have obtained a 'respectable' number of believers have we begun to shift on that account. The same would be true of the island people or any other relatively new faith.
Atheists simply don't take the number of people choosing to believe something, or the length of a belief's persistence, into account as to whether it is ridiculous or not. That sounds like 'a high horse' to some people, but it is really just using a correct, consistent standard for evaluating whether something is unfounded or not.
If someone comes up to me and says tomorrow, "I honestly, really believe that god is purple metaphysical octopus whose tentacles created the eight true planets", I am going to think this is ridiculous. I see no reason to grant any other religion any greater deference. If someone wants to present enough evidence to warrant deference for their specific religion, I am ready and willing to hear it. But, evidence is the only thing that should make any difference at all.
I am sure this stance does not persuade the unpersuadable, and it does piss them off. But, it is effective, over time, with people who are.