In Act I of The Merchant of Venice, the exposition and rising action unfold as characters are introduced and the problems begin. One of the problems is that Antonio, a Venetian merchant is worried about his ships that are yet at sea because he has made so many investments that he is rather extended, and if his ships do not arrive with their cargoes to be sold, he will be in financial straits. Added to this, his friend Bassanio owes him money, but needs more. Generously, Antonio agrees to procure three thousand ducats, but he must go to the loathed Jewish merchant Shylock and ask him because Shylock is greedy enough to loan him the money.
When Bassanio approaches Shylock with his and Antonio's proposition for a loan, Shylock is wary because he knows what Antonio has said about him to other merchants:
I hate him for he is a Christian:
But more, for that, in low simplicity,
He lends out money gratis, and brings down
The rate of usance here with us in Venice. (1.3.37-40)
Bearing hatred for Antonio mainly because he does not charge interest on loans and, thus, brings down the rate of interest that Shylock himself can charge, Shylock is at first reluctant to deal with Antonio. On the other hand, he would love to avenge himself upon Antonio for his lending methods and for his anti-Semitic remarks:
If I can catch him once upon the hip,
I will feed fat the ancient grudge I bear him.
He hates our sacred nation; and he rails,
Even there where merchants most do congregate,
On me, my bargains, and my well-won thrift, (1.3.41-45)
Shylock intends to renew an old and long standing grudge that he has against Antonio as a rival merchant and as a hated Christian. So, while at first Shylock wants nothing to do with Antonio, he agrees to loan him money because he is aware of Antonio's financial situation and believes that Antonio may not be able to repay him and he can then wreak his revenge by legally killing Antonio who agrees to pay with a pound of his flesh (Antonio would probably bleed to death if this much flesh were cut from him.)
In this scene, Shakespeare employs two of the greatest elements that foster hatred: religion and money.