By Gregg Birnbaum and Kevin Liptak CNN

(CNN) -- President-elect Donald Trump wished the world a Merry Christmas on Sunday -- on Twitter, of course.

Trump tweeted out a #MerryChristmas photo of him with his right hand raised in a fist and a Christmas tree in the background behind him.

The photo appears to have been taken at a recent Trump rally.

Later Sunday, Trump put out another tweet: "Merry Christmas and a very, very, very, very Happy New Year to everyone."

On Saturday, Trump sent a Happy Hanukkah message on Twitter with a photo of a lit menorah.

President Barack Obama also tweeted Christmas wishes on Sunday, writing, "The best part of the holidays is the time we share with those we love. On behalf of Michelle, Malia, and Sasha, Merry Christmas everyone."

On Christmas eve, Obama telephoned US service members, according to Deputy Press Secretary Eric Schultz.

"Last night, the President made telephone calls to US service members from each branch of the military who are currently stationed around the globe," Schultz said in a statement on Sunday. "The President expressed his gratitude on behalf of all Americans for the service and sacrifice of our troops and their families."

For his part, Trump sat (and kneeled at times) on Christmas eve for a two-hour service at the neo-gothic Bethesda-by-the-Sea church in Palm Beach, Florida.

He and Melania Trump, who are spending the holidays with their family at Trump's Mar-a-Lago resort nearby, entered without introduction just before the service began. The congregation offered a loud round of applause. The Trumps sat four rows from the front, with Secret Service agents in the pews front and behind them.

Throughout the service, Trump appeared engaged. He sang along to the well-known first verses of the Christmas carols, though once the songs entered the later, lesser-known verses he stopped.

The Trumps shook hands with people sitting near them, including their Secret Service agents.

The President-elect and Melania took communion just past midnight. Trump was seated along the center aisle, and every congregant who took communion processed past him on the way toward the front. A few people stopped to stay hello but not many.

Many people took photos of Trump inside the sanctuary of Trump. One woman was noticeably filming Trump as she walked past him.

The rector, who didn't mention Trump by name, described a Mexican Christmas tradition involving families and children going door to door for nine nights and he urged congregants to "let go of resentments" since they can consume you, suggesting instead people open their hearts to Jesus.

Afterward, the rector told CNN his message was intended for everyone, not Trump.

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