A New York State Supreme Court justice has ruled that financial records of the Unification Church headed by Sun Myung Moon must be open to the public.

Justice William Walsh, ruling on a plea involving the church's bid for tax exemption in two Westchester County areas, said Neil Salonen, president of the church, must release the records publicly, not in a private deposition.

An inspection of Unification Church financial records, scheduled for Sept. 25, was called off when the church, in meeting with Greenburgh town officials, discovered that two attorneys representing New York City also were to check the documents. New York is also opposing a tax exemption for Moon properties.

Unless Salonen secures an order from a higher court restraining the town from holding a public session when the church data is disclosed, the disclosure will be made on Oct. 10, according to Joel Sachs, Greenburgh town attorney.

The Unification Church has lodged two suits, upholding its right to tax exemption against two villages, Tarrytown and Irvington, both in the Town of Greenburgh.

In 1978, according to municipal tax records, it paid $326,329 in village, town, county and shcool taxes. Since 1975, it has been denied tax exemption on its Belvedere estate in Tarrytown and on 100 acres of additional property in Tarrytown, Irvingon and Greenburgh's unincorporated section.

Greenburgh has demanded that the church present all financial records of its nationwide operation, a listing of all national officers and a list of its publications before the church's suit comes to trial.

Town officials say they need the data because they contend the church is not a bona fide religious organization, the same stand taken by New York City.

According to state law, a religious institution may be granted tax-exempt status for its properties if it is a bona fide religious organization and if the properties are used exclusively for religious purposes. The town contends that the Unification Church also engages in propaganda and political activities.