A couple who disguised themselves as Strictly Orthodox Jews in order to infiltrate Chicago’s Jewish community have been unmasked as Christian missionaries attempting to proselytise “to bring Jewish people to believe in Jesus.”

The couple, going by the names David and Rivkah Costello, dressed in the traditional clothing of Orthodox Jews and prayed in local shuls, with Mr Costello taking a job in a local kosher supermarket and Mrs Costello reportedly babysitting local Jewish children.

An unnamed Chicago rabbi told the JTA that the couple had previously attempted to infiltrate the Chassidic community in Brooklyn, but had been discovered and asked to leave.

He said that an Orthodox Jew from Williamsburg, Brooklyn, had been visiting Chicago and saw David Costello in a shul there, prompting him to alert the rabbi of the congregation.

Speaking to JTA, Mr Costello claimed to “actually keep the Torah and the Mitzvos”, but admitted that “we want Jewish people to recognize Yeshua [Jesus] as Moshiach and as a Jewish Messiah.”

COL Live, an Orthodox news site quoted Rabbi Levi Notick, a rabbi from Chicago, saying he “met with the couple” and “they have beliefs of kefira [heresy] and Christianity.”

“He doesn’t deny any of it,” Rabbi Notick said of Mr Costello. “On the contrary, he insists that he is correct in his way, and has no regrets.”

JTA uncovered a November 2016 newsletter from an evangelical Christian group discussing how “David and Rivkah are willing to go into the darkest of alleys”, to “share the Good News [proselytising about Jesus]”.

It describes them as having taken “a very costly yet bold stand for the Lord…as they live kosher among Hasidim while serving Jesus as their Savior.”

The newsletter describes Chasidim as “usually deemed as too hard to reach and extremely resistant to the Gospel”, and “usually very warm and kind people, except when it comes to Jesus (Yeshua).”

In an unrepentant Facebook post, later deleted, Rivkah Costello did not deny the couple’s belief in Jesus, but said that those who had unmasked them had “brought shame to Judaism for how you have slandered us”.

Messages were shared widely throughout the Chicago Jewish community, warning people of the missionaries.

“Everyone is advised not to talk to them,” one message read.

“Please do not be a hero or a know-it-all, even if you may have met them and think they’re nice.”