When she opened the envelope that arrived, unsolicited, in the mail, Kate Duggan literally jumped for joy. It was a check for $141,700.50 — proceeds from the sale of the Lutheran Church of the Redeemer in Maywood, which was closing. Church leaders looked for a fitting use for the funds, and selected Family Promise of Bergen County, which helps homeless working families become self-sufficient. Duggan, the agency’s executive director, went to the Redeemer Lutherans’ new parish on Sunday, Holy Trinity in Hasbrouck Heights. Her message: “We treasure the faith you have in Family Promise.’’