There is a caveat to this question: your answer should go beyond the too-obvious point that Tartuffe is shown as a religious hypocrite. The problems the church had with this play go way beyond the fact that Tartuffe is a religious imposter. What is it about this play that the Church found so offensive?
Religion is obviously one of the play's central themes, but it is crucial to realize that the play intends to expose religious hypocrisy, not to attack religion overall. Tartuffe is defined by his outward displays of religious piety, and through them, he manipulates Orgon into overlooking his family's welfare. One could even understand Orgon's motive as wanting to feel close to God himself. Certainly, Moliere sees the absurdity and danger of such religious hypocrisy. However, through Cleante, the play reveals the significant distinction between hypocrisy and true spirituality. Cleante suggests that a true holy man does not brag about himself or viciously condemn others, is not prideful or showy, and does not aim to curry political or social favor. Cleante stresses that true holy men of virtue do exist, but it is part of their nature not to be recognized as such. Therefore, the play aims to mock religious hypocrisy, while suggesting its biggest fault is the way it maligns and compromises the glory of true religion.
