It is illegal in Israel to proselytize among minors. It is also prohibited to engage in missionary activities among adults when economic incentives are offered.
After over eight hours of detention, Jamie Cowen, a former president of the union, and his wife, Stacy, were permitted to enter Israel only after they agreed to sign a document that they would not engage in missionary activities during their stay.
The Cowens are in Israel to visit their two daughters, one of whom is an Israeli citizen. The other is in the process of obtaining citizenship after she and a group of other Messianic Jews won a Supreme Court case against the state.
The Cowens and their daughters all identify as Jews but believe that Jesus is the messiah.
"This type of religious discrimination would be expected of Iran, not Israel," said Jamie Cowen, a US immigration lawyer, a few hours after he was released by immigration police.
"In the US we imprison individuals suspected of terrorism. Here apparently one can be jailed for his religious convictions. This is a case of blatant discrimination against basic rights. It is a story of a bureaucracy run amok. Someone has to crack down and bring in people of integrity."
Cowen said he had visited Israel about 10 times, and had been active in social causes via the Knesset Social Lobby.
"I've brought $100,000 in humanitarian aid to Israel. We've provided lone IDF soldiers with about $50,000 in aid. This is unbelievable," he said.
The Interior Ministry, which directed the police to arrest the Cowens, said they had classified information regarding missionary activity.
"The Immigration and Population Authority has reliable information that the Cowens were involved in missionary activity prohibited by Israeli criminal law during their last visit to Israel," a ministry spokesman said.
"This is the reason they were detained. As soon as they agreed to refrain from any missionary activity they were allowed in."
The Cowens arrived in Israel on a flight from Frankfurt at 3 a.m. They were arrested at passport inspection and placed in detention at the airport.
"As an immigration lawyer I have visited many detention facilities for illegal immigrants. This one was particularly dirty, smelly and overcrowded," Cowen said.
According to Cowen, the Union of Messianic Jewish Congregations has 90 member congregations with membership ranging between 50 and 400 per congregation.
Calev Myers, founder and chief counsel of The Jerusalem Institute, which provides legal advice and representation to messianic Jews, said the Interior Ministry was filled will clerks who identified with a strictly Orthodox definition of who is a Jew.
"During the years that Shas controlled the ministry they made sure to appoint clerks who were willing to carry out their policies," Myers said.
"As a result, Israel is the only Western country where basic freedom of religion is denied. Today those who being discriminated against are messianic Jews. Tomorrow it will be Conservative and Reform Jews."
Myers said anti-missionary organizations such as Yad Le'achim often tipped off Interior Ministry officials regarding messianic Jews attempting to enter the country.
However, Meir Cohen, a Yad Le'Achim activist, said that while it was true that his organization did provide the ministry with information, they were not involved in the Cowens' case.
Cohen said the ministry had its own intelligence unit that gathered information on missionaries and on messianic Jews who were ineligible for Israeli citizenship due to their religious convictions.
The Supreme Court has ruled that Jews who embraced Christianity are not eligible for Israeli citizenship. However, the court has also ruled that people who are not Jews according to Orthodox standards, but who are eligible for Israeli citizenship under the Law of Return do not forfeit this right if they adopt Christian beliefs.