Tartuffe represents religious hypocrisy. He cons Orgon by pretending to be a religiously devoted and pious person who denies himself and spends his time involved in charitable works to help the poor. He persuades Orgon to sign his house over to him and to leave his inheritance to him.

Tartuffe has not a religious bone in his body and even tries to seduce Orgon's wife. He is all good words and no good deeds.

Tartuffe exposes the vice or evil of cheating and lying to get hold of another person's possessions, but he also exposes Orgon's vice of being too trusting. As the genuinely good Cleante says

The truly pious people . . . are not the ones who make the biggest show.

Orgon's vice is being too willing to believe words rather than looking at what a person does. He longs to find an individual of true Christian goodness in an evil world, and so he falls for a person who tells him what he wants to hear. At the same time, he misses the family members and people around him who are truly good, even if they don't entirely express themselves in the religious language Orgon wants to hear.

Hypocrisy is undoubtedly the most significant vice on display in Tartuffe. But such hypocrisy, as it is demonstrated by the title character so wantonly, is only possible due to another vice: credulity, or, to be more specific, Orgon's credulity. The gullible Orgon is so taken in by Tartuffe's feigned piety that he's blind to all his guest's numerous faults. Everyone else in the play can see Tartuffe for the total fraud that he is, but up until the end, Orgon remains utterly mesmerized by this unspeakable charlatan. It's not that Orgon is a bad man; it's just that there appears to be a gaping emotional and spiritual hole at the core of his being that Tartuffe is only too ready to fill, or at least appear to fill.

Tartuffe, in Moliere's play of the same name, represents many vices, indeed, criminal behaviors, having committed so many crimes as to be arrested by a Gentleman of the Guard! Among these would be fraud and false witness against innocent individuals, i.e., Orgon. The vice that Tartuffe is generally associated with, in relation to the theme primary of the play, is hypocrisy.
The primary theme of Moliere's satire is religious hypocrisy versus true Christian values. Tartuffe is the representative of hypocrisy while Cleante is the representative of true Christian values, and Orgon is the one against whom the definitions of these terms is played out, making for a rather neat plot device.
Hypocrisy in our era seems a small vice because it is a common epithet to bestow on people who don't always behave according to church traditions or who feign friendship. But the way Moliere paints hypocrisy, he means it as a grievous act of serious proportions.
"Values" also seems a modest sort of word in our present age but when cast in an analogous position next Tartuffe's style of hypocrisy, "values" takes on much larger scope than the lifestyle choices that "values" is generally associated with today.
As in the above, the problems Tartuffe represents are many: insinuating oneself into another's affections and good esteem on fraudulent grounds; manipulating individuals to gain selfish ends; willfully misrepresenting yourself in order to take advantage of someone's position. However, the main problem Tartuffe represents is that of defrauding an entire family out of its rights and happiness: a daughter wed against her will, a son disinherited, a wife made the object of ghastly attentions.