One lesson Christian conservatives learned, Mr. Sears said, is that lower court decisions that violate what he considers to be original constitutional principles can lead to more dangerous assaults. Griswold v. Connecticut, for example, the 1965 Supreme Court ruling that Connecticut could not ban the use of contraceptives by married couples, was a travesty, he said, because it established a new right of privacy, used in 1973 to justify legalizing abortion in Roe v. Wade.

In 2003, the alliance worked against what became another landmark ruling in Lawrence v. Texas, which declared laws against “homosexual sodomy” unconstitutional. Its lawyers feared that the decision would help open a legal path to same-sex marriage.

The group originally focused on channeling donations to other lawyers as well as training more Christian lawyers in issue-oriented litigation, which remains a major part of its work. Its summer fellowship program has drawn 1,300 law students, and some 1,700 practicing lawyers have attended training sessions.

But the alliance soon expanded its own legal team, joining a cluster of like-minded, nonprofit law firms including Liberty Institute, which is devoted entirely to “religious liberty” issues; the American Center for Law and Justice; the Becket Fund for Religious Liberty; Liberty Counsel; and the Pacific Justice Institute. Alliance Defending Freedom, which changed its name in 2012, relies on private donors, whom it does not disclose.

“A.D.F. and the other groups wanted to counter more liberal legal forces, and they have largely achieved that goal,” said Douglas Laycock, an expert on law and religion at the University of Virginia Law School. “On the whole, they work at pretty high levels, and they’ve got a lot of boots on the ground.”

Along the way, the alliance has sometimes ruffled the feathers of sister organizations. When California state officials declined to defend Proposition 8, the amendment banning same-sex marriage, the alliance took up the cudgel. But when it lost in federal court in 2010 in the case, Hollingsworth v. Perry, Liberty Counsel complained publicly that Alliance Defending Freedom had excluded it and had performed poorly.

Many of the alliance’s legal victories (it says it has an 80 percent success rate) have involved defense of religious activities and symbols at universities and in public spaces.