After going unselected in the 1978 NFL draft, Christopher was signed by the Denver Broncos as an undrafted free agent.[2][3] However, he did not make the final roster, as he was cut in August.[4] Christopher signed with the Kansas City Chiefs in 1979, but was again released before the start of the season.[2] However, he re-signed with the team that October following a knee injury to starting strong safety Jerry Reese.[2][5] Christopher earned the starting strong safety spot after three games.[2] He played in nine games as a rookie and recorded two interceptions.[6] Christopher started all 16 games in 1980, recording 78 tackles and two interceptions.[7] He was moved out of the starting lineup in favor of Lloyd Burruss during the 1981 season.[8] Christopher was released in August 1983.[8]