A second Christian group is investigating whether the BBC discriminated against Christians by showing Jerry Springer - The Opera.
The opera received thousands of complaints when it was shown on TV
The Christian Institute wants a judicial review of the BBC decision to broadcast the show on 8 January.
Characters played Jesus, Mary and God in the hit musical shown on BBC Two.
Group director Colin Hart said: "The BBC has a duty to respect the religious beliefs of its viewers." Prayer group Christian Voice took similar action.
"Genuine religious debate and criticism is one thing, but this show is an offensive, spiteful, systematic mockery and wilful denigration of Christian belief," added Mr Hart.
The BBC received 47,000 complaints before the musical was broadcast, and hundreds of Christian protesters rallied outside BBC buildings before and during the show.
BBC director of television Jana Bennett defended the musical as "a really good piece of opera that had something to say".