In Act I, Scene iii of The Merchant of Venice, explain Shylock's words, " Yes, to smell pork; to eat of the habitation which your prophet the Nazarite conjured the devil into! I will buy with you ....nor pray with you."
In The Merchant of Venice, Shylock agrees to loan Antonio money, on behalf of Bassanio. Bassanio has done the negotiating and now that Shylock has agreed he wants to talk to Antonio. Bassanio invites him to "dine with us." Shylock and Antonio have a huge dislike for each other and there is an animosity between the Christians and the Jews, a lack of trust.
Shylock will not therefore dine with Antonio and Bassanio as they show no respect for his religion serving pork, such as "the Nazarite, conjured the devil into." He will not be tricked by them. He confirms that he will trade and do business "and so following" but the most important functions of eating, drinking and praying, he will not do with Christians.
These lines refer to differences between Jewish and Christian traditions. Readers of the period would have been intimately familiar with the Bible and thus the lines would have been easily comprehensible to them.
For Jews, pork is unclean. Although Christians generally do not follow the dietary laws set forth in the Old Testament, religious Jews, especially in this period, would follow the Biblical precept:
And the swine, though he divide the hoof, and be clovenfooted, yet he cheweth not the cud; he is unclean to you. (Leviticus 11:7)
Since Christians engage in dietary practices that Shylock considers sinful (including using the same dishes for meat and dairy products), it would be impossible to eat with Christians without violating his own religious beliefs.
The term "the Nazarite" refers to Jesus, who is described in the Bible as being from Nazareth. The mention of "the Nazarite" conjuring the devil into pigs refers to a story in the New Testament of two men being possessed by demons. Jesus performs an exorcism, expelling the demons from the men. Then:
So the devils besought him, saying, If thou cast us out, suffer us to go away into the herd of swine. (Matthew 8:32)
Jesus then causes the demons to transfer to a herd of pigs and the demons in pig form rush into a stream, drown, and die. Thus Shylock is suggesting that for Jesus pigs are also unclean, and by eating pork Christians are violating not just Old but also New Testament doctrines.