I basically see it this way: There are two basic types of Zionism. There is religious Zionism, which came about as Jews were driven from their homeland by the Romans in 70 ce. Jews felt that they had to return to the land that they came from, just as the bible prophecized. Then there is modern political Zionism which developed from Theodore Herzl in the late 19th century. Bascially, Herzl saw that Jews had no future living as strangers among the Gentile nations, and that for SAFETY reasons, Jews should go back to their homeland.
To me, there is tremendous validity in both types of Zionism, and even though I believe in the fulfillment of Biblical prophesy, I think Herzl was right on the money in his grim assessment of the Jews' place among the nations.