The Jew of Malta opens with the ghost of Niccolò Machiavelli, the man who literally wrote the book on playing dirty to achieve and maintain power. With that kind of introduction, it shouldn't surprise you that most characters in this play are down with lying and cheating. For some characters, like Ferneze, deceit is mostly a means to an end; with Barabas, though, it feels like deceit becomes an end unto itself. Barabas goes from devising plots to achieve recognizable goals (get back his money, kill Lodowick) to living for the plots themselves. But here's the question: are we supposed to condemn all these lies? Or is this just something leaders have to do?
While Barabas himself dies, deceit and manipulation win out in this play—Ferneze doesn't emerge victorious because he's morally superior, but because he turns out to be the most successful practitioner of these kinds of tactics.
While many characters are willing to employ trickery and deceit, Barabas's special joy in plotting and lying makes him the real Big Bad of the play.