You know what? Let's elaborate a little.
You see, this claim - that Zionism isn't a Jewish idea - stands behind claims like "most Zionists are Christians!" and "Zionism is a Christian movement!" and the like. It's not explicitly there, but it's implied. The poor Jews would never choose, on their own, to do such a horrific thing as... gags Zionism. They just want to argue and shake their lemon at G-d or whatever!
Yeah. So. History lesson. But first, I want to go a bit into what Zionism is. Now sure, every person wants to give their shnekel on this at this point, but frankly, the common jumblr definition of "self determination for Jews in their ancestral homeland" has confused me at first so I want to rephrase it: Zionism is the desire to return to Eretz Yisra‘el, the land where our ancestors lived, and establish there an independent country.
Now, you may hear many people claim that Zionism under this definition is ancient, way older than the 19th century's Zionist movement. Then again, you might hear that it was only born with said movement. The former is closer to the truth, with some slight caveats. For centuries, ever since the first Jewish exile, we've had the desire to return to Eretz Yisra’el. You can see that in how Jews were emigrating there throughout the centuries. From Rambam, to Rabbi Yechiel of Paris, to Ramban, and Rabbi Yehudah haLevi, and Rabbi Yehudah haChasid, and Rabbi Yosef Karow, all the way to Rabbi Yisra’el of Shklov and Rabbi Menachem Mendel of Vitebsk, and many more throughout the centuries. It was written in songs. We pray towards it, and pray that we will get to see it. It's even written into our legal code that emigrating to EY is preferable to emigrating from it. So at least that part of what Zionism is definitely existed throughout the centuries.
The "self determination" part - the independence - is a bit different. Last time there was a serious, nearly successful attempt to establish a Jewish state in the land, the Romans crushed it and didn't allow us to bury our dead for at least a week. And since this time, Jews rarely ever had anything close to military power. So there may have been some attempts at revolts, but they tended to be unsuccessful. There were also, though, the false Messiahs.
To make a long story short, the point of the Mashiach in Judaism (as opposed to the Christian conception of Christ) is of a decidedly human king who will gather us from our various diasporas, return us from our exile to our land and lead us. False Messiahs tended to at least attempt to emulate that, to various degrees of failure. Evidently from their name, they didn't succeed. A big example for that is someone I wrote of just last week: Shabbtai Tzvi, who was said to be going to kill and overthrow the Sultan. So, this is some evidence that the hope for independence in our homeland was also existent and strong among Jews.
After that, I would like to note one thing that is almost completely unique to the Zionist movement: it took practical rather than mystical steps towards this latter goal, including diplomatic negotiations with the local rulers and other world nations. In this, BTW, I think David Reubeni was the closest guy to attempt anything similar by trying to negotiate for Portuguese canons. He still failed, of course, but that's a fascinating attempt.
So here we get into it: Herzl, father of the Zionist movement, was Jewish. The attendants of the Zionist congress were Jewish. The idea of coming back to Israel was Jewish.
The idea for doing that didn't come from weird Christians thinking Jews need to return to Israel for the Second Coming to occur. They may have grown to support it, but the Zionist movement was Jewish and for Jews. Not part of outside pressure.
Of course, some people might tell me I shouldn't be proud that my religion supports colonialism. The answer to that is simply that there are only two workable frameworks where this is colonialism: if Zionism was a non-Jewish movement - which I just detailed how it's rubbish - or if you believe a form of the Khazar theory and think it makes Jews European. This is also rubbish and has been proven wrong. So if you please, kindly consider the fact that your ignorance of Jewish history is a you problem and that you shouldn't attempt to tell Jews what their religion and culture is like, especially with this dismal a knowledge about it.