Act 1, Scene 3: How can we account for Antonio's generosity concerning Bassanio, but his discourteous behaviour toward Shylock?

Certainly there is the juxtaposition of Christian caring (Antonio and Bassanio) vs anti-Semitism against Shylock. It is interesting that Elizabethans felt Shylock's more tragic scenes to be comedic. Elizabethan audiences expected anti-Semitic overtones throughout the play. On another level, there is the definite sense of a homoerotic connection between Antonio and Bassanio. It is not dealt with directly but there are undertones.