Shylock in The Merchant of Venice by William Shakespeare was written by a Christian for a Christian audience. From a theological point of view, the Church of England's theology followed Luther's formula that all people are "simul justus et peccator" (both righteous and sinners at the same time). This applies to Shylock as well.
Shylock's famous "I am a Jew" speech in Act III Scene 1 gives evidence of the way that Christians have mistreated Jews and how much Shylock feels that he is mocked, scorned, and treated as less than human by his Christian compatriots.
On the other hand, Shylock's desire for vengeance, and specification of one pound of flesh as a forfeit seems unnecessarily cruel. As Shylock himself realizes, his being oppressed and victimized has made him bitter and vindictive.
There is no real way to measure the degree of blame to be apportioned to Shylock or to the surrounding society, although for Christians to act as brutally toward Shylock as Antonio acted, there is a strong case made that Shylock was more sinned against than sinning. Nonetheless, the most important point is that all forms of bullying and ethnic prejudice can brutalize both the oppressors and the victims.