Lolo Jones -- U.S. Olympian and self-proclaimed virgin -- says "Fifty Shades of Grey" is an abomination ... and people should boycott the movie because it glamorizes unholy sex.
Jones -- who's also a devout Evangelical Christian -- went to Twitter and wrote, "Funny how some people think there's nothing wrong with 50 shades of Grey. God didn't create sex for that purpose."
She added, "Watch another movie."
Jones then explained her stance ... saying the movie's hypersexual plot makes people feel that sex for pleasure is the answer to emotional pain.
"Some ppl medicate pain by being more and more physical to where if they are ever alone they can't feel any peace," Jones wrote.
The tweet is in direct contrast to Russell Wilson, another devout Christian who says it's not only OK to see the movie ... but admits he took in a screening last week and said he thought it was "great."