In the opening scene of the fourth act of Othello is a four-line quote that shows how easily Othello is manipulated. The scene opens as follows:
Iago Will you think so?
Othello Think so, Iago?
Iago To kiss in private?
Othello An unauthorized kiss!
Iago Or to be naked with her friend in bed
An hour or more, not meaning any harm?
Othello Naked in bed, Iago, and not mean harm?
It is hypocrisy against the devil.
They that mean virtuously, and yet do so,
The devil their virtue tempts, and they tempt heaven.
In these four lines Othello shows himself to be incredibly gullible, or worse than gullible. He actually believes Iago's assertion that Desdemona and Cassio have been spending time together in bed naked and the possibility that they might have no desire or intention of engaging in sexual intercourse. Iago seems to be intimating that this is the sort of thing that is customary in the Venetian high society of which Othello, a complete outsider, is ignorant.
Othello seems like someone who is trying to be broad-minded and urbane but cannot help expressing his very strict conservative beliefs about proper conduct. Othello, being a Moor, probably has had an education based on the Koran, which teaches rigid laws of human behavior. A married woman who committed adultery in the Muslim world could be stoned to death.
Iago seems to be enjoying himself in this opening scene. In addition to his other motives for destroying Othello's happiness, Iago may just enjoy deceiving and manipulating people, seeing how far he can go. Iago is cunning. Cunning people are not necessarily wise and rarely creative but more often parasitical. They cannot create anything but have to exploit others. Like Cassius in Julius Caesar, they are "very dangerous."