This work expands upon recent historical analysis of Shakespeare's 'Othello', which has foregrounded issues of race, colonialism, and feminism, in order to show how the discourse of religion might affect our understanding of this play. It specifically looks at how the discourse of Catholicism, itself a highly contested topic in Shakespeare's world, affects our understanding of Desdemona, whom the play so directly compares to perhaps the most divisive and controversial figure of the entire 'Reformation' period, Mary the Mother of God. Explaining how this comparison is developed and clarified by Shakespeare, this book explores the difference our interpretation of Desdemona's 'Marian' dimension might make to critical understanding of the tragedy of 'Othello'.