Christian Zionism is a movement within Christianity that insists on the Jewish right to seize the entirety of the land of Israel including the West Bank, Gaza, and for some, all of the land between the Nile River in Egypt and the Euphrates in Iraq.
What this means, concretely, is that for a growing number of Christians there can be no peace between Israelis and Palestinians. Justice, for Christian Zionists, is the removal of all Palestinians from God-given Jewish land.
The Christian Zionist movement is deeply embedded in contemporary Christian culture. It is the dominant expression of media Christianity, and is prominent among military chaplains and Christian military. In other words, this is no small irrelevant theological trivia. This has life-altering political significance.
At the root of much Christian Zionist dogma is the notion that the Bible contains predictions of how the world will end. These predictions are found throughout both the Hebrew Scriptures and apostolic writings, but they are most pronounced in the Book of Revelation. In a nutshell the theory states that one day Jesus will return to earth and slaughter all those who oppose his iron-rod rule. Where Israel fits into this scenario is that the Jews must be living in their land. The Jews are God's chosen people to reveal the wisdom and will of God. Right before Jesus returns, several thousand Jews will acknowledge that Jesus was indeed the incarnation of God on earth. All of this happens in the midst of global catastrophe and chaos, and the rise of an antichrist (kind of sweet Jesus in reverse ... ironically, kind of like the Jesus who comes back and slaughters everyone).
The theory assumes that the Creator is basically pissed off at us. Like a drunken father who beats his wife, abuses his children, and kicks the dog, the God of Christian Zionists is heavy into dominance and submission, which trumps the kindness and mercy of love. Such a God can choose the Jews one day, and when they act out, this God can abuse them the next, eventually obliterating them entirely. Similarly, Christian Zionists on the one hand bend over backwards to honor the Jews and empower the state of Israel. But on the other hand, all of this is done so that Jesus will return to slaughter all the disobedient, including the Jews who won't convert to Christian Zionism.
Here's the point. We're in the midst of a culture war, yet we are ambivalent about religious teaching, thinking it has no political manifestation. Evangelists rent space in our public school buildings, yet we think that exposing our children to such words and deeds will have no cultural effect. Christian Zionism has an agenda that desires to shape the politics of this nation. Beginning in righteousness, it ends with the blood of the unclean shed. In the words of Jesus, "keep awake."