(RNS) The growing Hispanic population in the United States is sure to impact our politics. In fact, it already has.

Hispanic voters matter. Just ask Republicans Meg Whitman in California and Sharron Angle in Nevada, who alienated Latino voters and ended up losing elections they were expected to win.

The warning to any future Whitman or Angle is clear: there will be 1.5 million new Hispanic voters in 2012, with many more to follow within the next decade.

That irreversible demographic fact also has important interreligious implications, especially among Christians and Jews.

For the past thousand years, the majority of Christians and Jews lived inEurope or North America. It’s where major religious institutions, movements and leaders found a home, and where the first successful efforts in building mutual respect and understanding between Christians and Jews took root.

But the landscape is changing.

Today, the Christian populations of Europe and North America are relatively stagnant — part of the reason why Pope Benedict XVI attacked “secularism” and religion’s declining role in recent visits to Britain and Spain. Meanwhile, in South America, Africa and Asia, all branches of Christianity are thriving. The so-called “Third World” of geopolitics is actually the “First World” of church growth.

Until recently, most evangelical, Pentecostal and charismatic Christians in the U.S. traced their family roots to Europe. Now, large numbers of Hispanics — more than a few of them former Catholics — are joining Protestant churches.

In the U.S., the rising number of Hispanic Catholics will soon eclipse the shrinking number of Catholics of European descent. Numerous dioceses, faced with decreasing seminary enrollments and ordinations, import priests from overseas to fill vacant pulpits. The nation’s bishops, too, are slowly being replaced by younger bishops whose families didn’t come through Ellis Island.

The early encounters between American Catholics and Jews in the 19th and early 20th centuries were often overshadowed by suspicion, hostility, and prejudice. But Catholics and Jews had at least one thing in common: their immigrant families all faced the same systemic anti-Semitism and anti-Catholicism in employment, housing, and education.

Because of history and geography, Hispanic Christians have had few, if any, direct encounters with Jews, and the reverse is equally true. It’s a recipe for misunderstanding and disagreement unless we find ways to bring the two communities closer together.

There’s a similar story within the global Jewish community. Israel will soon surpass the U.S. to become home to the world’s largest Jewish community, numbering nearly 7 million people. More than 850,000 non-European Jews from Africa, the Middle East and Asia have arrived in Israel since its creation in 1948; many came with large families that have followed the biblical commandment “to be fruitful and multiply.”

Many first-time visitors to Israel are sometimes surprised that Israel is not the outpost of white European colonialism that many critics falsely charge. Instead, it is an authentic and diverse Middle Eastern nation, not one that’s dominated by Americans or Europeans. As a result, many Israeli Jews have had limited contact with Christians and Christianity, even in the region that gave birth to Christianity.

The ancient Greek philosopher Heraclitus taught that “You cannot step twice into the same river.” Our demographic “rivers” are rapidly changing, and the religious or political leaders who don’t understand this are doomed to drown.

(Rabbi Rudin, the American Jewish Committee’s senior interreligious adviser, is the author of the recently published “Christians & Jews, Faith to Faith: Tragic History, Promising Present, Fragile Future.”)