"Threats against the President-elect will be taken very seriously," said US attorney Dunn Lampton.
Christopher, who is from Wisconsin, was arrested by the Secret Service in Brookhaven on Friday, after two threats were posted on the Internet, The Telegraph reported.
Federal prosecutors said that he was charged with threatening to kill Obama for what he claimed was "the country's own good".
The criminal complaint was sealed until the 42-year-old suspect's appearance in a federal court. A judge ordered Christopher to be held until a bail hearing next Thursday.
He is said to have made two threats on January 11 and January 15.
The security scare came as Obama is preparing to take office as America's first Black president at his inauguration in Washington next Tuesday.
It followed the uncovering of a suspected neo-Nazi plot to kill Obama last Oct shortly before the US election.
The plot centred on Tennessee, where the Black civil rights campaigner Martin Luther King was assassinated 41 years ago.
Two neo-Nazi skinheads were accused of planning to rob a gun shop and go on a murder spree at an African-American high school, with Obama as their final target.
Last August four people were arrested after allegedly planning to assassinate Obama at a convention centre in Denver, Colorado.&13;&13;