You asked me to address the following: You said:
“Nobody” who admits to atheism gets elected because generally, people first vote along party lines, then according to their pet issue (be it taxes or abortion or school vouchers), then according to general congruence of issues, then maybe according to gender… and so on, with “religious denomination” not cracking the Big Three or maybe even the Big Five."
Then you are in fact saying that whether or not a person is an atheist should make little or no difference, if religious denomination is not part of the big three or even the big five.
Fine. Therefore, one would expect that since atheists are a small minority but certainly not nonexistant in the class of educated people from which most politicians come, there should, out of thousands of governors, state assemblymen, state senators, congressmen and federal senators elected over the past few decades be at least SOME number of avowed atheists. Even if avowed atheists are just one or two per cent of the population, one per cent of say, five thousand is still 50. Now, I admit I do not know the exact number of individuals elected in the US over the past couple of decades, but it must be in the thousands. Nor am I saying that the number of avowed atheists elected has to be 50. But when it is soooo rare that one guy admitting it last month and one California Governor in 1939 is all we have, some prejudice is operating somewhere. Either being an atheist is a bar to gettiong elected or else there ARE atheists in Congress and the Senate who are too smart or scared to admit it because they know the level of prejudice that exists.
You said:
“Besides, atheists are such a minority that even if they voted en masse for any one candidate, no matter what electoral district, be it local, State, or Federal, their combined numbers would not make a dent in the results. The bloc “atheists” does not generate large enough percentage points to be noticed.”
Now you are getting completely irrelevant. I never said that it was a matter of atheists “electing” other atheists by their numbers. Take that, straw man! 
For that matter Jews are only 1.4% of Americans. There is no majoritively Jewish state. I do not know how many majoritively or even heavily Jewish electroral districts there are, but can there be that many if they are 1.4% of the population? But as someone pointed out, 6.7% of (federal?) legislators are Jewish. We have had and have now many fine Jewish senators. Good. Fine. That proves that while anti-semitism may exist, it is not all that active among American voters. I congratulate US voters for that.
Now compare that with the fact that a majority of Americans have said they would NOT vote for an atheist for President even if he had the qualifications. Is there a prejudice operating there? You bet!