A prom picture has unexpectedly drawn anti-Christian sentiments on social media and the journalist who shared the photo expressed surprise over the angry reactions.

Anchorman Frank Somerville of KTVU posted the prom picture on his Facebook page, saying he had received it from the mother of one of the teens in the picture. He wrote in the caption, "So impressed with these young people on their prom date ... They all said Grace before eating and were all well behaved."

He then explained that the mom had shared the photo to make the point that it offers a different take on teenagers making headlines because of bad behavior.

"It's really nice to see," Somerville remarked.

Some people on Facebook, however, reacted negatively to the photo. One user said that saying Grace before meals wasn't something that should elicit praise while another commented that "Saying grace over your food says nothing of your moral compass, integrity or character." 

Others took aim at the Christian faith.

"So now we are supposed to praise kids for praying to an invisible man in the sky for animals that were slaughtered so they could eat?" said one Facebook user.  "So tired of Christians pushing their beliefs onto everyone else."

Others were more positive in their responses, though.

"Good grief. They were praying.....not 'forcing' their beliefs on other people. This is sad and funny to me," read one comment.

"I agree with the people mentioning that you don't have to be a Christian to be a good person...but it is lovely to see this group expressing gratitude in the way they feel is appropriate," said another.

Defenders of Somerville's post were also quick to note that the journalist did not say in his post that the teenagers were Christians, nor that they were better than non-Christian teens.

One of mothers of a teenager in the photo told Yahoo that the photo showed her daughter behaving as an adult with good manners.

"I couldn't be more proud and blessed that she is a humble and kind person," the mom said. "That's what this picture shows...maturity and good judgment."

In his own defence, Sommerville said he was "surprised" by some of the comments.

He wrote on Facebook: "I wasn't trying to imply that you have to be a christian to be a good person.. what i see from these kids is that they are respectful... that they are humbled... and that they are appreciative for what they have. ... i could care less whether they are religious.... but by saying grace it shows me that they have those qualities.. and those are the qualities... regardless of whether you believe in god ... that i admire.."