When Shylock wants to meet antonio,bassanio invites him to dine with them.Why does Shylock refuse to eat with him?

Shylock is a Jew and Antonio is a Christian. Shylock has felt humiliated and oppressed by Christians in the past. Shylock knows the only reason he is being asked to dine with them is because they want something from him. 

Shylock refuse to dine with them because they are Christians and pork-eaters. He says that he is ready to buy and sell, talk or walk with them, but won't eat, drink and pray with them.