When the northern and southern wings of the Presbyterian Church recently voted to reunite after more than a century of separation, one reason was the influence of northerners who have migrated to Texas.

When the Houston City Council recently put new restrictions on developers, the closest that Houston has come to zoning, it was also partly because of pressure from northerners who have moved to Texas.

And when graduates of Brooklyn's Tilden High School recently held a reunion in Dallas and had to turn away several hundred people for lack of space, that, too, was a sign of changes that have come because of migration from the North.

From religion to politics to cultural values, northern immigrants have begun to make lasting changes on the Sun Belt. Many have assumed leadership positions in local politics, neighborhood organizations, churches and the arts, and many are questioning the way Texans have traditionally done business. Their numbers are now significant enough to make them a force when they choose to exert themselves.

"We look at things differently," said Don Callenius, who came to Texas when the Boy Scouts of America moved their national headquarters from New Brunswick, N.J., to Dallas three years ago.

But it is clear from conversations with many of these newcomers that living in the Sun Belt has changed them as well. They have adapted to a slower pace and to a style of living oriented to the outdoors. Many of them say that they are more involved in their churches than they were before coming to Texas and that they have become more conservative in their political views.

In the summer of 1980, Ric Robinson was on strike for the second time in eight years in northern Indiana when he decided to come here. Along with his brother-in-law, Robinson came to Dallas, camped by a lake and soon found a job. Today he is an established Texan--and vehemently opposed to labor unions.

"Here, if you shine, you shine," he said recently. "I hope unions don't come to Texas. I feel no desire to again be a union member."

Together with native Texans and immigrants from other nations, the northern migrants like Robinson and Callenius are forging a new regional style, neither northern nor southern nor particularly western. If anything, it may be an indicator of tomorrow's American center.

"In Texas, it's clear from voting patterns that the northerners are voting more conservative than back home and yet may be liberalizing the climate here," said Joseph R. Feagin, a sociology professor at the University of Texas.

If the United States is a melting pot, its hottest points today are in places like Dallas and Houston, and the effects of the northern migration are likely to be even more evident as this rapidly growing region continues to mature.

The impact of the migrants has created a backlash among the native Texans, and even some newcomers recognize that something significant is being lost through their arrival.

"The thing I really admired about Texas is something we're losing at a rapid rate, and unfortunately it's because of people like me. That's Texas pride," said John Steffens, who moved from Peoria, Ill., to a Dallas suburb in 1981.

Steffens isn't the only person to notice. A Dallas company considered running an advertising campaign with the theme of Texas pride, but found little enthusiasm for the idea with a group of residents it surveyed.

Texas immigrants may have embraced Texas chic with more fervor than the natives, but there is nothing lasting in their commitment to the styles and symbols that have been historically important to native Texans.

The "northerners"--and that word is used to describe the many Californians who have moved to Texas as well as immigrants from the East and Midwest--have come in successive waves: oil company managers, Boy Scout executives, airline pilots, teachers, advertising executives, computer programmers, and more recently unemployed carpenters, auto workers and steel workers.

After more than a decade of migration, population experts are still trying to understand the newcomers. "We don't have a good picture of who the migrants are," said Dudley Poston, director of the Population Research Center at the University of Texas in Austin.

Those who have studied the migration to the Sun Belt believe the first to come were predominantly conservatives. They helped establish the Republican Party in Texas and supported the 1978 election of Bill Clements as the state's first Republican governor since Reconstruction.

But their voting habits are not conventionally conservative, because it was with the support of many newcomers that Kathy Whitmire was elected mayor of Houston in November on a program that is fiscally conservative but socially liberal.

The latest wave of migration has brought Democrats: unemployed union workers from Michigan and Ohio and New York and elsewhere.

"The newest migrants are distinctly different," said Rick Ryan of the public opinion analysis firm of V. Lance Tarrance and Associates in Houston. "They're more pro-union, they're more pro-zoning, they're less imbued with Protestant ethic, and they're younger," he said.

Some have been swallowed up by their surroundings and have tried to capitalize on them. Ira Zack came from California about three years ago, opened a country-western nightclub and helped perpetuate Texas chic. But he is tiring of that now and said the most interesting thing to happen in his club recently was the standing ovation given to a group that sang "New York, New York."

Others are attempting to alter their new environment. John Larson came with the Boy Scouts in 1979, and the new landscape of suburban Dallas gave him the opportunity to organize a neighborhood association that he believes will affect local government. "They don't have a positive approach to their long-range planning," he said. "Those of us who come in with other expectations are a threat to the natives."

The two cultures have not been fully integrated, with suspicion on both sides. The migrants rave about the friendliness of native Texans, but say that hospitality goes only so far. "Where it gets real tough is when you get into the areas of religion, politics and race," one man said. "That's when the friendliness vanishes."

Newcomers also joke that it is difficult to find native Texans. In part that is because the migrants have settled in the newest suburbs. One of these Dallas enclaves, called Plano, grew more than 300 percent between 1970 and 1980, and most of the increase was because of people from out of state.

"We have few native Texans in our congregation," said the Rev. George Beimler of the First Presbyterian Church of Plano.

Beimler, who came from New York, said the major difference his congregation feels about being in Texas is the number of fundamentalist churches in the area. "When Jerry Falwell or Bailey Smith comes up, they don't like it," he said, referring to the leader of the Moral Majority and the Baptist minister who said that God does not hear the prayers of Jews.

Southern Baptist churches are the dominant denomination in Texas and are still growing, but so are denominations historically strongest in the North, such as Methodists, Lutherans, Catholics and Presbyterians.

The Rev. John Anderson of the First Presbyterian Church of Dallas serves as moderator of the Presbyterian Church in the United States, the southern wing of the church. He says he can see the influence of the northern migration on the way his church is searching for his replacement.

"They're looking in all 50 states," he said. "Three years ago, they would have been looking only in Dixie."

Anderson and other Presbyterians also said that the influx of northerners to Texas helped move along the process of reunification of the church, which could be completed by next year. Texas is one of a number of states where the churches already belong to both wings and in which the Presbyteries, or governing bodies, are unified.

"I don't think the only thing that's influenced reunion is the northerners, but they've helped," Anderson said.

For some people, the migration to Texas has given them the chance to display openly political views they have long held. Jim Sproul is one. He and his wife left Boston for Dallas in 1980. A computer programmer and conservative Republican, Sproul is now a GOP precinct chairman in a Dallas suburb and pleased by his new environment.

Said Sproul of the advantages of his adopted home: "I've shoveled my last snow and fought my last Kennedy."