More than two centuries of Protestant domination on the Supreme Court will end if Samuel Alito is confirmed as its next justice. For the first time in the nation's history, five Roman Catholics -- a majority -- would be on the high court.

Yet news that the son of an Italian immigrant father, someone who grew up in a suburban New Jersey parish where he served as a lector and later married, doesn't carry quite the power it might have in the days when Kennedys ran for the White House.

Catholics have become part of the nation's political mainstream -- far removed from the blatant anti-Catholic prejudice that once permeated American culture. They are as divided as other Americans on abortion and other social issues that will be a focus of Alito's confirmation hearings -- making an outpouring of religious pride for the conservative jurist less likely.

''The Catholic community is not going out dancing in the streets of Boston tonight because of this nomination,'' said James Davidson, a Purdue University sociologist who researches religion and Supreme Court justices. ''But it still represents a significant development in American religious history.''

Protestants have been so dominant on the court that half of the justices have come from just three denominations: the Episcopal, Presbyterian and Congregational churches, he said.

Only two Protestants would remain on the Supreme Court -- David Souter and John Paul Stevens. The two other justices -- Ruth Bader Ginsburg and Stephen Breyer -- are Jewish.

Analysts said Alito, as the fifth Catholic, was a less controversial religious choice than Harriet Miers, whose adult acceptance of born-again Christianity was dissected for clues about how she would vote on abortion. President Bush helped make religion a central issue in her failed nomination, saying it was a factor in selecting her for the high court.