In the days leading up to Christmas, Brenda Lans, a Miami law-firm administrative assistant, sang religious carols with other Lutherans to harried travelers at Miami International Airport.

Jorge Rollo, an office manager, oversaw the sprawling Gift of Bethlehem tableau on the grounds of St. John Neumann Catholic Church in southwest Miami-Dade.

Teenage siblings Coraliz and Dennis Morales shivered in the chilly darkness outside Faith Presbyterian Church in Pembroke Pines as characters in a Living Nativity.

Count them all among the Christians who believe that taking religion public during the late-December shopping frenzy helps make “Keep Christ in Christmas’’ and “Jesus is the Reason for the Season’’ more than bumper-sticker slogans.

Whether in small groups — the Rev. David Imhoff of Grace Lutheran Church in Miami Springs called his 13 carolers a “flash mob for Jesus’’ — or casts of hundreds like the Gift of Bethlehem, the activities become missions for the faithful.

“On a spiritual level, it was so rewarding,’’ said Lans, 55, who isn’t in a church choir and described her singing contribution as “backup noise’’ to those with good voices. “It’s good to get back to the old traditions of caroling which give you the true meaning of Christmas...I felt uplifted doing that.’’

Another caroler, Elizabeth Maldonado, said that singing “Away in the Manger,” “Hark! The Herald Angels Sing,” and “Silent Night” for TSA agents, travelers and rental-car agents fulfills an obligation to evangelize, but in a way that doesn’t put people off.

“That’s the greatest commission, to go spread the Gospel,’’ said Maldonado, 53, who sang with her husband, George Sr., 52, and son George Jr., 13.

“Jesus commanded us to do that...Christmas is about the birth of our Savior, but some forget and some have not been told,’’ she said. “The only way to reach them is through love, not to criticize. You can’t push God into their lives, but you can show Him by your actions.’’

Coraliz, an 18-year-old Flanagan High School student, said she was freezing on Friday night when she spent two hours as a shepherd in the Living Nativity scene, as traffic whizzed by on Taft Street, but she didn’t mind.

“Advent is really special,’’ she said. “It’s a time when you honor Christ and thank Him for everything he has done for you, and you have to remember that this day of Christmas is the day that He brought His son to save us. As a Christian, that’s the biggest day of the year. I think it’s really easy to forget what we’re celebrating, and it reminds people what the point is.’’

“We get so wrapped up in Santa and shopping and parties, which are all wonderful, but in reality, this is the birth of the man who gave way to our salvation, and that’s to be celebrated,’’ said Rollo. He called the Gift of Bethlehem, which recreated life in the town where Jesus was born — right down to the lepers, horses, and open-fire bread bakers — “a celebration of our faith and spirituality, and that 2,000 years ago, Mary and Joseph put their faith in God and had this baby.’’