Bishop John Spong of Newark, N.J., one of the Episcopal Church's most controversial liberals, threw down another challenge to conservative critics when he ordained a practicing homosexual to the priesthood. The ordination in Hoboken is generating a new round of criticism from church conservatives who have been in almost a perpetual state of confrontation with Bishop Spong ever since he took the helm in Newark in 1979. Robert Williams, 34, a deacon and director of a ministry to gays and lesbians operated by the Diocese of Newark is not the first gay person in the Episcopal Church to be ordained. The Rev. Ellen Barrett, a lesbian and deacon, broke that barrier when she was ordained by Bishop Paul Moore of New York in 1977. But the ordination of Williams is notable for the way it focused on his homosexuality. The Diocese of Newark publicly announced the plans to ordain Williams five days before the ceremony, saying Bishop Spong would "celebrate an unusual and probably unique sacramental act by ordaining an avowed, non-celibate gay man to the Episcopal priesthood." The swiftest criticism of Spong's action came from the newly formed Episcopal Synod of America, a traditionalist organization founded last summer that counts six active Episcopal bishops among its members. The ESA bishops asked Spong not to conduct the ordination. Bishop Clarence Pope of Fort Worth, the ESA president, said the ordination would represent a disregard of "historic Christian moral standards." In a Dec. 8 letter to other bishops of the church, Spong acknowledged that the ordination was likely to generate "debate and controversy." But that debate, he said, might make it possible for growth in understanding homosexuality. Spong told bishops that the ordination of Williams would be "a step into honesty and integrity" for the Episcopal Church. According to officials at Episcopal Church headquarters in New York, there is no church law that specifically forbids ordination of open homosexuals. However, Spong's actions fly in the face of a 1979 resolution passed at the church's General Convention in 1979 which said it is "not appropriate" to ordain practicing homosexuals or those engaging in sexual relationships outside marriage. Spong contends the resolution is advisory, not binding. In a prepared statement, Presiding Bishop Edmond Browning, the top official of the Episcopal Church, said the resolution still represents the "mind of the church" on ordination of practicing homosexuals. Nonetheless, Browning said he hoped the ordination would "encourage positive debate rather than polarization." He emphasized that the ordination of Williams was not carried out by Spong acting alone but followed the approval of the diocese's Commission on Ministry and Standing Committee. Williams is a graduate of the Episcopal Divinity School in Cambridge, Mass. He was made a deacon of the diocese in June 1989 at about the same time he founded Oasis, a diocesan ministry dedicated to counseling gay and lesbian individuals and organizing educational programs on homosexuality.