Atheists are not the "worst of the worst" in Islam simply because the concept did not exist in the 7th century.
The concept existed, it just wasn't called "atheism."
As for the "worst of the worst," I think most academics would agree that in the Quran, such concepts are not based on what a person says, it's based on a relative accounting of their actions, and every human (of mature age and sound mind) will be accountable, including Muslims.
Islam's enemies are the groups it struggled against and tried to coopt in its early history: the Jewish tribes in the Arabian Peninsula. Mohammad tried and failed to convert these tribes and the insults and setbacks he suffered at their hands became doctrinally enshrined in the religion
Most of Mohammad's struggle was against the Meccan polytheists. The Jews have also been labelled "the people of the book," which is a very honorable title. Their actions in their own history have been criticized, and they were also criticized in the Bible. But Muslims don't have an exclusive concept of salvation, like Jews/Christians, or any monopoly over Heaven.
...and made them the eternal enemy of the faithful.
The "eternal enemies" of God in the Quran can be grouped in three:
1) Anyone who assumes political dominion over God's creation by rejecting Divine Law
2) Anyone who assumes spiritual dominion over God's creation via intercession based shenanigans
3) Anyone who assumes economic dominion over God's creation via interest-based lending
This 3rd set, by the way, has been criticized the most severely in the Quran, I think. Those engaging in "Riba" (interest based lending), are said to have declared
war against God, because of their economic exploitation, which can be argued to be most directly responsible for the suffering of not just humanity, but the entire ecosystem of the planet.
This is because the hated Jews occupy and hold Islamic holy land
Jerusalem was never actually that holy for Muslims. The only "holy land" in the Quran is the Masjid al-Haram in Mecca.
The Muslim-mythology of Jerusalem (which you mentioned) is just another one of those myths that Muslims have told themselves so much that they themselves have started to believe it. It's gone to a point where most Muslims now believe the Al-Aqsa Mosque mentioned in the Quran is the one in Jerusalem, which is ridiculous, because everyone knows that mosque didn't exist at the time of the revelation. The Caliph Umar built that mosque years after the Prophet had already died, when the Muslims captured that territory from Roman Byzantium.
The real reason why Israel is such a sticking point, is because that land is a very strategic piece of real-estate, and has been since the time of the original Crusades. All the mythology that has been built around it came much later, probably after the first Crusades. The strategic/geographic value of that territory is what's important, and it cannot be left in foreign hands, because it cripples lines of communication on land and through the Mediterranean.
Mohammad had barely anything to say about China.
It doesn't mention the region I'm from either, but I'm not complaining, because the audience of the Quran has been clearly defined as
all humanity. There's no 'special' group in Islam. Whenever specific groups have been mentioned, they have also been criticized e.g. both the Jews and the Arabs have been criticized in the Quran. Honestly, I think most of Human culture has been criticized in the Quran because of its slavish, exploitative and irrational traditions.
The problem, is that these days, Muslims themselves are guilty of most of the things the Quran criticized. And we are suffering the exact same consequences which we were warned we would suffer if we didn't act right.
