The Eastern European Zionists were the ones who had been brought up with Yiddishkeit and then threw it away. They were the former maskilim who had come to realize after the pogroms of the 1880's that their Haskalah had not gained them any safety in exile. In the words of Rabbi Avigdor Miller:

The 1870s and 1880s marked the beginning of pogroms in Russia. Because the Maskilim attempted to estrange themselves from the Torah and to draw near to the Gentiles, G-d caused Czar Alexander II, who had begun his reign with tolerance, to change his ways. There was a pogrom in Odessa (1871), the capital of the Maskilim, in order to convince them that by rejecting Judaism they could not gain equal rights. Pogroms took place subsequently in other places, and the press carried on a campaign of anti-Semitism, measure for measure for the press campaign of vilification carried on by the Maskilim against the Torah and its proponents. The May Laws (1882) prohibited Jews from residing in certain places in Russia, in Divine retribution for abandoning the law of G-d, and for desiring to reside among the Gentiles and be lost among them. The Torah leaders used these developments to point out the futility of irreligion and assimilation as methods of gaining equal rights as citizens.

The pogroms caused a great upheaval among Russian Jews. The Maskilim had preached that Jews should forsake the study of the Talmud, become enlightened and be like the gentiles, and then they would no longer be hated by the gentiles. When the pogroms came, the Maskilim were deeply shocked and disillusioned. Their dream bubble had now burst, for the mobs had attacked the educated Jews in the wealthier districts with the same hatred as they had displayed toward the poor Jews in the worst districts. The disciples of the Maskilim were now left without Judaism and without civil rights.

"They sacrifice to previously unknown gods, new ones, recently come; their fathers did not fear them." (Dvarim 32:17) Why did Moshe Rabbeinu emphasize new idols? Are not the old idols just as bad? The answer is that an old idol loses its attraction after a while. People realize that it was really nothing; they become disillusioned. But the yetzer hara is ready with new idols. Thus, even as the Haskalah was dying out, something new was taking its place - something even more dangerous.

The Maskilim were succeeded by two major groups: the socialists and the nationalists, or Zionists. To some people in America later on, Zionism was a form of coming back to Judaism. People who knew nothing at all and had no connection with their people felt that by becoming Zionists they were identifying with the Jewish people. But in Eastern Europe, Zionism was a radical leftist movement, and a movement away from the practices of the Torah. It was a movement of breaking down all the old practices and attitudes. They preached patriotism for the Jewish people, and they encouraged the dream of a homeland, where they would build a new life, throw away all the old practices of exile, the Torah, the yeshivos, the synagogues and the rabbis, and be a nation like all nations.

The disciples of the assimilationist Haskalah had been terribly disillusioned after the pogroms. They recognized that a Jew cannot give up his allegiance to the Jewish people and assimilate the gentiles would not let him. The mobs attacked the Jewish doctors, dentists and apothecaries, just as they attacked the Jewish water carriers. They decided that they had to return to the Jewish people, but they needed a substitute for the Torah, because they wanted to continue in their old beaten path of license and irreligion. Thus they created the new idol called Nationalism, or Zionism. The same writers, in the same magazines and newspapers, now began to hammer away at Judaism under a new banner, the banner of atheistic Nationalism.

They preached their new ideology as a substitute for the Torah: You can be the best kind of Jew if you are a nationalist Jew, and you don’t need any Judaism. You don’t even need G-d. A whole school of writers arose at this time such as Achad Haam, who taught this along with philosophy and textbooks. This was the time when the enemies of the Torah became the nations leaders. The Maskilim were never able to be accepted as leaders, because they were too openly assimilationist. But now a more subtle enemy arose, under the guise of real Jews, the best Jews, nationalist Jews, and they succeeded in becoming the nations leaders.

(End of quote from Rabbi Miller.)

Rabbi Chaim Soloveitchik once described the transition from Haskalah to Nationalism in a letter: "Not only my grandfather [the Netziv] supported the founding of settlements in Eretz Yisroel, but I myself liked the idea for a long time; however, the actions of the students from Charkov caused me to withhold my support. I always remember that great day [Jan. 21, 1882] when the students of several universities gathered in the great synagogue of Kiev. They fasted all day and confessed their sins, that they had become estranged from Judaism. And they came out with the slogan, "House of Jacob, let us go!" If only there had been someone who had said at that high moment, "Let us return to Hashem! Come, brothers, let us begin to be careful about keeping Shabbos and kashrus." Nothing of the sort. All of them remained the same irreligious people they had always been. They came to Eretz Yisroel and did not improve their ways even a bit. But they crowned Ben Yehuda as their teacher, and they spread in our holy land heresy and lawlessness. Certainly we must oppose Zionism.” (Printed in the periodical Digleinu, 5720, and in the book Mara D'ara Yisroel, v. 2 p. 18.)

Herzl, on the other hand, was from a completely Reform and assimilated background. He was not a "shanah upiresh" and he did not understand the mentality of the Eastern European Zionists. His interest in Zionism was aroused by the Dreyfus trial (1895), but even before that he had felt that the Jews were in danger and he had looked for a solution. Some people think Herzl was interested in assimilation and shmad for its own sake, pointing to his suggestion of conversion of the Jews to Christianity in 1893. But the truth is that that suggestion was made in the context of his search for a way to solve the "Jewish problem" (i.e. anti-Semitism). In the words of the Encyclopedia Judaica:

“From October 1891 to July 1895 Herzl was the Paris correspondent of the Vienna Neue Freie Presse, the influential liberal newspaper of the time. During his Paris sojourn he became absorbed by French political and social problems and particularly by French parliamentary life; a selection of his articles on the latter topic was published in book form (Das Palais Bourbon, 1895). The growth of anti-Semitism in France stirred Herzl's interest in the Jewish problem, and an article by him on the subject of French Anti-Semites appeared in the Neue Freie Presse as early as August, 1892. After a two-year stay in Paris, Herzl came to regard the Jewish problem as a social question that could be solved by the organized, mass conversion of Jewish youth, as well as by their affiliation with the socialist movement. Before long, however, he realized that this was not the solution. In the drama Das Ghetto (later renamed Das Neue Ghetto), which he wrote in the fall of 1894, Herzl sought to put the Jewish problem on the theater stage and thereby raise public discussion. In a way, this move was the beginning of a new approach to the Jewish problem. It was Herzl's hope that a public debate of the Jewish problem in place of its previous restriction to the realm of private discussion would lead to a satisfactory solution based on the mutual tolerance and respect of Christians and Jews. In the drama, Herzl rejects assimilation and conversion as solutions to the problem. The Dreyfus Case led Herzl to draw his final conclusions. He attended the trial as the Neue Freie Presse's correspondent and was a witness to the riotous behavior of the Parisian mob when the innocent Jewish officer was publicly humiliated in a ceremony stripping him of his military rank (January 5, 1895). The shouts of "Death to the Jews" ringing in his ears, Herzl became convinced that the only solution was the mass exodus of the Jews from their present places of residence, infested by Anti-Semitism, and their resettlement in a territory of their own. He decided to apply himself to the realization of this idea.”