That is not true for the overwhelming majority of Israelis who see, everyday, that conservative Christians (not Roman Catholics) are their best allies in the world. There are major Fundamentalist Christian organization with millions of supporters who continually pressure Congress on behalf of Israel and are many times more influential than any Jewish or Israeli lobby (real or imagined).
I have no genuine idea why American Jews are so wrong. They are confused by centuries of Catholic Christian and Lutheran pogroms. They have also endured centuries of proselytizing.
What they don't know are that:
-1) Protestant Christians were the first Zionists. Mormons went to Palestine in the 1840s. German Protestant Templars went in the 1860s as Zionist settlers. This is 25 years before Herzl even thought about Zionism.You do have to wonder how long and how many dead Jews it will take for American Jews to change their anti-fundamentalist Christian views.
-2) Protestant Christians refer to Israel as the 'holy land' and they mean it. What could make a better friend than someone who really loves your country?
-3) The greatest friend the Jews have ever had in 2,500 years of our history is an Evangelical Christian who publicly committed America to support Israel under all circumstances. That is G.W Bush. Compare G.W. Bush to the current president who, this week, is giving American Medals of Freedom to two people who publicly hate Jews and Israel. The current president who chose an open hater of Israel to be his national security adviser. Who has spent six months telling Israel to sterilize the people in many towns and cities in Israel so they won't have children (it is called the Obama no-natural-growth plan)... while telling the terrorist Palestinians they will have everything they want with no effort.