Confronted with a popular music subculture which is predominantly antipathetic to Christianity, the charismatic-evangelical members of rock band U2 double code their lyrics in such a manner that Christian references are hidden from mainstream listeners and media while being readily recognizable to their Christian fans. The device of allusion is especially amenable to this end, as the meaning of an allusion can only be considered by a reader or listener who possesses the requisite competency in respect of the evoked text(s). Through their utilization of biblical allusions, U2 therefore construct two different, perhaps even irreconcilable, groups of listeners—a knowledgeable Christian in-group and an unknowledgeable non-Christian out-group. With detailed reference to U2's songs, this paper examines the covert tendencies of allusion and the manner by which it is able to engage the listener's intertextual imagination. The paper also distinguishes a secret or hidden allusion from a generic allusion on pragmatic and socio-cultural grounds, and demonstrates the potential of secret allusions to increase semantic indeterminacy. Lastly, the paper examines some examples of the reception of the U2 song 'Magnificent' which demonstrate the effectiveness of U2's secret biblical allusions in creating two largely discrete groups of listeners.