This play revolves around money and the conflict arises due to monetary problems and differing attitudes towards money. Images of commerce are also common in play. Money itself is not condemned but it is the obsessive love of money that stultifies and corrupts. In the play, Shylock represents possessiveness and the Christians, generosity.
Shylock's character is distorted by his obsession over money, which is seen when the audience see him mourning over his loss of ducats and cursing Jessica as being "dead at my foot". This gives him the cynical attitude to human relationships and the audience views him as the "bad guy".
Shylock feels that money should be well manipulated to his advantage, which is seen in his practice of usury to get his revenge by signing the bond with Antonio. This reveals Shylock's crafty side and portrays him evilly. Furthermore, these manipulations further develop the disagreement and hatred between Antonio and himself, evident before we first see them together in Act 1 Scene 3.
Shylock is also stingy with his moneys. His aim is to "breed" money and would not lend money if he does not benefit. At the start of Act 1 Scene 3, we see Shylock carefully thinking about his advantages upon signing this bond. Through the above mentioned three ways, Shylock is portrayed as the antagonist very effectively.
The Christians on the other hand are generous with their moneys and use money to liberate and ennoble and in the process create happiness. Antonio and Portia, both richly furnished, are people with respected virtues. They lend money to help people without further hesitation.
Antonio's helpfulness can be seen where he willingly helps Bassanio by borrowing money to lend him and telling Bassanio that "My purse, my person, my extremest means / lie all unlocked to your occasions". .
Portia's generosity is seen later when she offers to pay Shylock double or double the double of the amount allocated in the bond in order to help Antonio, whom she has never met before.