When Mongan Nyman and her classmates exchanged Halloween candy in October 2000, Morgan's included messages like "Costumes are cool but heaven is awesome!" But Robert Davidovich, principal of Cushing Elementary School in Delafield, Wis., said the second-grader's holiday messages violated the separation of church and state.

Then he made Morgan go to each classmate and take the candy back.

That afternoon, she got off the school bus crying, her mother said. She cried all night, too, once becoming so upset she threw up.

Three months later came Valentine's Day, and Mr. Davidovich refused to let Morgan pass out cards with sayings like "Jesus loves you." This time, her parents, Jeff and Shanon Stockhausen, called attorney Mathew Staver.

Mr. Staver, head of Liberty Counsel, a religious-liberty law firm in Orlando, Fla., filed suit in March 2001, charging that the school district had violated Morgan's rights to free speech and free exercise of religion. It took just weeks for the district to settle out of court. That April, the district changed its policy to allow students to express their religious beliefs on campus, and publicly apologized to Morgan in the Milwaukee Journal Sentinel.

On Valentine's Day 2002, Mr. Staver received a religious card from Morgan-and so did every member of her third-grade class.

A grade-school fracas over Valentines and Halloween candy may seem an oddball case for any constitutional lawyer who hopes to be taken seriously. But liberal civil-rights groups, including the ACLU, have learned to take Mat Staver very seriously. His Liberty Counsel files bulge with victories, and his win-loss record is a liberal's bad dream. Liberty Counsel wins more than eight in 10 of its cases, and it now has one headed to the U.S. Supreme Court. Mr. Staver in February will argue before the high court McCreary County, Kentucky vs. ACLU of Kentucky. At issue: whether public displays of the Ten Commandments violate the Constitution. The usual opponent is, of course, the ACLU.

Like several of the other two dozen or so Commandments cases now inching through the civil courts, McCreary involves so-called "contextual" displays in the Kentucky counties of McCreary and Pulaski. In such displays the Commandments appear alongside other historic documents such as the Magna Carta and the U.S. Bill of Rights. Courts are sharply divided about the monuments: Currently, four federal circuit courts and one state Supreme Court say they're constitutional, while three federal circuit courts say they aren't.

McCreary marks the first time since 1980, when the high court purged the Commandments from public-school classrooms, that it will review the issue. And it is the first time the court will receive full briefs and hear oral arguments in a Ten Commandments case.

For Mr. Staver, the case is part of a case-by-case approach to winning back lost liberties. Take little Morgan Nyman's case, for example. To some lawyers, trivial stuff: small school, small town, not much press potential, and certainly no money in it. But to Mr. Staver, Morgan's suit was much more: a clear-cut case of religious discrimination that, if won, would not only right wrongs, but also lay another brick in the foundation he is building through Liberty Counsel.

"Our strategy is to regain lost religious liberties incrementally," Mr. Staver said. "You have to take the long view, select the right cases, make the right legal arguments, knowing where you are contextually in history."

Friends say this fits with Mr. Staver's personality. "Mat is extremely methodical," said Art Ally, Liberty Counsel board member and president of the Timothy Plan Family of Mutual Funds, who has known Mr. Staver for 15 years. "He is very intelligent, but he can apply that intelligence in the most thoroughly logical way. . . . There are a lot of intelligent people who couldn't come in out of the rain."

Mr. Staver says he became a Christian as a teenager. His father was an abusive alcoholic who left the family when Mat was only 2 years old. Left alone in Charlotte Harbor, Fla., to raise seven children, his mother worked three jobs to support them, often on Sundays. A professing Lutheran, she began attending a local Roman Catholic parish because it was the only church in town offering multiple service times.

"I was religious," Mr. Staver says of his early years, "but in retrospect I would not say I was a Christian." He became one at age 18 when evangelist Art Swenson arrived in Charlotte Harbor to preach a series of sermons on end-times prophecy. "It was the first time any organized religion had ever emphasized the Bible to me," Mr. Staver remembers. During five weeks of marathon preaching, he only missed one night, and finally professed faith in Christ.

When Mr. Swenson transferred his services to the local Seventh Day Adventist church, Mr. Staver was surprised, since he hadn't known the revival was denominational. But his family eventually joined that church, and he eventually attended a Seventh Day Adventist seminary in Michigan, graduating first in his class in 1982. The denomination assigned him to pastor three churches in the Lexington, Ky., area.

But during college, Mr. Staver's study of Scripture took him on a theological path that diverged from his denomination's teaching, eventually leading him to the Baptist church.

But not as a pastor. Before switching belief systems, he switched careers, the result of an epiphany sparked when a group of evangelical pastors invited him to watch a video on abortion that featured photos of a baby developing in the womb.

"I was astounded . . . it was as though I had been asleep this entire time," he said. The baby in the film wasn't, as he had imagined, a blob of tissue, but "indisputably a human life, one God had created. Yet the law had changed to the extent that human life was now something permissible to take. . . . That was when I realized that the law could either help us or hinder us in the expression of our faith."

American law, and its historic Judeo-Christian roots, became a passion that carried Mr. Staver through the University of Kentucky law school, where he graduated in 1987. Two years later, he opened Liberty Counsel.

The pro bono firm first tackled cases involving religious-liberty controversies in public schools, then branched out to defend pro-life protesters, on-the-job religious expression, and the traditional family. Tax records show that Liberty Counsel litigated 82 cases last year on a budget of $1.4 million, 75 percent from direct donations, of which Mr. Staver paid himself a salary of $75,000. Recently, the group has crossed legal swords in high-profile gay-rights cases, including the attempt to overturn gay marriage in Massachusetts (a loss), and the attempt to turn back San Francisco Mayor Gavin Newsom's same-sex marriage licenses (a win.)

His track record has won Mr. Staver respect among activists fighting on the other side. "He has a credible reputation as a lawyer," said Rev. Barry Lynn, executive director of Americans United for Separation of Church and State. "He's a formidable opponent. I think most [liberal church-state activists] would probably agree with that."

Asked to reveal his own greatest weakness, Mr. Staver pauses, mind whirring almost audibly as he sorts through prudent replies. Then: "I don't mean this to sound boastful, but I'm pretty content with who I am," he said. "I'm not perfect, but I'm content with who I am." Still, he says he's his "own worst critic. I'm always Monday-morning-quarterbacking myself, thinking about how I can do or say something better."

One improvement, from his perspective: His views on religious liberty have widened to accommodate the reality of a multi-religion nation. He recounts a case he argued in 1989 against a Seminole Community College teacher who planned to show his students the blasphemous film The Last Temptation of Christ.

"I wouldn't do that now," he said. Instead, he would ask for equal time, for the opportunity to have a movie like The Passion of the Christ shown elsewhere on campus.

"I think I've become more principled in my thinking on free speech-that it's for all of us or none of us," he added. "The First Amendment allows for messages we don't like. How we combat that is by allowing truth beside error, not truth instead of error. . . . If you put Christ beside Satan, truth beside falsehood, right beside wrong, you will invariably have God's Word not returning void. Truth will triumph."

Right now the question is whether Liberty Counsel will triumph in McCreary vs. ACLU. Mr. Staver hopes the case will at last cut through the massive tangle of conflicting case law surrounding Christian public displays.

But there is more at stake in McCreary than monuments. Liberty Counsel's petition to the Supreme Court also asked the justices to revisit the so-called "Lemon test," the 1971 "excessive entanglement" decision by which courts often judge the constitutionality of intersections between government and religious expression.

Mr. Staver's team didn't just ask the Supreme Court to review the Lemon test, they also asked the court to establish a new test. And the court said yes.

Was Liberty Counsel's move too bold? Might the delicate 5-4 majority that often marks this court's decisions on social issues tip this time in the wrong direction? "It's true that the new test might not be a test we like," Mr. Staver admitted. "But the old test is one that nobody likes. It has resulted in hopeless disarray among the courts on church-state issues."