What is the general consensus(I realize this is general indeed, as individuals differ) on folks like polytheists and atheists?
Since Judaism teaches that there is only One God, the Creator, who isn't a rock or river of person or anything else of this world, we believe that polytheists are greatly mistaken. Any Jew who converted to a form of polytheism would be considered apostate.
The thing about atheists, is that they are defined by what they are NOT. They lack any belief in God, and have no religion. Jewish perception of atheists vary, and it is definitely a far more nuanced thing than polytheism. This is because on one hand, they lack any belief in God, which is core in Judaism. But the bigger question is, are they keeping the commandments?
I have known Orthodox Jews who certainly do think that Atheists sin when they do not acknowledge God, but when I used to attend a Reform synagogue, there were actually quite a few atheists who attended regularly and were welcome there.
I have a good friend who is an Orthodox Jew and also an atheist. He will tell you that he is a Jew first, and an atheist second. He once told me the story of an atheist Jew, a tailor, who planned to attend the Yom Kippur service. His friend asked him why he would do that as an atheist. He replied, "Jews go there to be with God. I go there to be with the Jews."
It is worth noting that Jews also look more leniently on those who are not raised in Judaism, or are otherwise not familiar with Jewish teachings.
As for me personally, I have absolutely no problem with atheist Jews. I find that in general they are very moral people. I don't think they choose to be atheists. They simply don't experience anything that would indicate to them that there is a God.
I'd like to tell you a story that has greatly informed my own view.
Reb Zusha, seeking to learn and understand the world more deeply, decided to study with the apikorsim—men who were deeply studied in Torah but who had rejected it. His fellow Hasidim were shocked and concerned. How could such a righteous man associate with those who denied core aspects of Jewish faith? Reb Zusha explained that he wasn’t abandoning his beliefs or giving in to their ways. Rather, he saw value in understanding different perspectives, even those that opposed his own. He famously said, “I suck out the juice and spit out the pits.”