A new law, designed to curb the activities of Christian missions in Israel, which recently was passed almost unnoticed by the Knesset (Israel parliament) is causing a belated storm of protest.

The protesters, including Knesset members, Jewish groups and the United Christian Council of Israel representing several Christian groups, some of which are fundamentalist, claim the law is not needed, is impossible to implement and only will arouse emotions and deepen the rift between Jews and Christians in Israel and abroad.

The law, which does not mention Christian missions by name, makes it a criminal offense, punishable by up to five years in jail to give money or something worht money with the intention to tempt another person to change his religion. Persons accepting bribes in return for changing their religion also will be prosecuted.

The law was presented as a private bill by Rabbi Yehuda M. Abramowitz of the ultra-orthodox Agudat Israel party. It came at a time when most public attention is Israel, and in the Knesset, was focused on the spectacular political events in November begining with the visit of Egypt's President Sadat to Jerusalem and peace negotiations that ensued. It picked up most surprising support from some of the most liberal members of the Knesset and was brought for its second and third reading without previous annoucement, when most of its opponents were absent from the Knesset floor.

"They handled it almost like a military operation," said a representative of an American Jewish organization, who tried to find out about the law. "Rabbi Abramowitz himself was frank when he told me he would refuse to talk to me as long as the law was not yet on the books and that there would be little point to talking after it had been passed."

The Israel Interfaith Committee, which strives to encourage a better understanding among all religions in Israel, asked to be invited to testify before the Knesset law committee to which the draft law was referred, or at least meet with its chairman, David Glass, of the National Religious Party, but never received a reply. When a meeting with Glass finally was fixed, it was canceled shortly before it was about to take place. This did not prevent the law from being presented for approval by the Knesset.

In justifying their proposal, the originators of the law claimed that they know of "tens" of cases in which missions enticed families to convert by offering them financial support, jobs or even assistance to emigrate from Israel to Canada or to some country in South America. However, members of the law committee of the Knesett said in interviews that no hard evidence of such practices was presented before the committee.

Mrs. Shulamit Aloni, who is the sole representative of the Citizens Rights party in the Knesset and was the most vociforous opponent of the proposed law in the Knesset debate, claims that according to her investigation there were only four cases in which Jews converted to Christianity in 1974, nine cases in 1975 and six cases in 1976. In these cases bribery could not be proven nor was even alleged.

Mrs. Aloni and other critics charge that supporters of the legislation had two goals in mind: to enable the Agudat Israel party, which is interested mainly in legislation of this nature, to draw some benefits from its support of Prime Minister Menahem Begin's government, and to provide a vent for some of the deeply rooted resentment against methods of Christian coercion which Jews felt for centuries when they were a minority in Christian society.

Gideon Hausner, who in the present Knesset is the sole representative of the Independent Liberal Party and in the Past advocated laws which would limit the power of the rabbinical courts, surprised many of his colleagues when he supported the new law. Hausher, the prosecutor in the Eichmann trial, explained in an interview that "over and above being a lawyer and a liberal (I am) a Jew and as such cannot divorce (myself) completely from the history of compulsory conversion throughout the ages."

The Israeli press, which hardly noted the passage of the law to curb the missions, in recent days has begun to question the wisdom of the law and query its probable impact on relations between Jews and Christians.