They have tried letter-writing, petitions and a lawsuit, all to no avail. So now the Christian congregations that are weeks away from expulsion from New York City’s public schools are focusing on more-religious tools in their arsenal: prayer, fasting and repentance.

About 200 people gathered at Calvary Baptist Church on West 57th Street on Monday night to pray for God to soften Mayor Michael R. Bloomberg’s heart. The pastors at the service, including one who was among those arrested last week at a “pray-in” outside the offices of the city’s Law Department, also said they would pray outside a Bronx school on Thursday before the mayor gives his State of the City address inside.

They are pressing the city to let dozens of churches continue to hold worship services in school buildings, despite a court decision allowing the city to eject them.

“If the body of Christ hurts, then let my body suffer along with it,” said Dimas Salaberrios, pastor of Infinity New York Church in the Bronx, who said he had been consuming only water for nine days and would not eat until the city reversed its position. “We are hoping that someone will research a little further to see that the churches have been doing good works, and that it will be self-destructive to the city to kick them out.”