A municipal conciliation court, in a novel ruling, has ordered former members of a synagogue in suburban St. Louis Park to pay pledges they made to a building fund for the synagogue.

The B'nai Emet Synagogue took the ex-members to court to enforce pledges ranging from $167 to $1,000, contending they were bound by enforceable contracts when they made their pledges.

In a separate but related suit, the synagogue also won a ruling that a husband and wife are legally obligated to pay $333.34 for past annual membership dues.

The policy of enforcing religious obligations in a civil court appears to be highly unusual. A spokesman for the Minnesota Rabbinical Association said he had heard of dunning letters signed by lawyers to collect pledges but that he had never heard of such letters being followed by a lawsuit.

The Roman Catholic Archdiocese of St. Paul in Minneapolis does not regard its fund appeals as legally binding, a spokesman said. A spokesman for the Southeastern Minesota District of the American Lutheran Church said he knew of no church that had tried to enforce financial pledges legally.

County Attorney Tom Johnson said he could not recall any lawsuits to collect fund-drive pledges being filed by religious, charitable or community organizations. Court records showed, however, that in 1961 the Minneapolis United Hospital Fund sued to collect on a $300 pledge made four years earlier.

Whether pledges can be interpreted as legally binding depends on whether they meet the legal criteria for contracts, lawyers said. Kent Magnuson, the synagogue's lawyer, said he contended in court that the pledges met the criteria.

Daniel W. Hergott, one of two conciliation court referees involved in the case, said the synagogue used the pledges as collateral for a bank loan. He said that satisfied him that a legal contract existed.

Hergott and Allen I. Saeks, the other referee in the case, do not have to prepare written judgments because conciliation courts use exceptionally informal procedures. The referees, who function as judges, merely announce orally their decisions, which are appealable to the district court. No appeals have been filed in the synagogue case.

The ultimate problem is not so much legal as practical, said a lawyer close to the case. He noted that suits to collect pledges could backfire and cause people not to contribute to voluntary fund drives, lest they be taken to court when unable to fulfill the pledges for reasons sometimes beyond their control, such as finding themselves short of cash.

The former members involved in the suit were listed in court documents as two married couples and an individual man.

Arthur Silverman, who along with his wife was assessed $167, said that he had made payments on his pledge monthly until he and his family left the synagogue and that he thought the rest of his obligation ended when they severed ties.

Another couple indicated the judgment against them would be paid. Lynn Benson, expressing shock, said she and her husband had left B'nai Emet in early 1979 but are being held liable for dues covering the rest of that year.

Rabbi Sylvan D. Kamens of B'nai Emet said he had discussed the case with the former members but prefers not to comment.