How we cite our quotes: (Act.Scene.Line)
Quote #1
I count religion but a childish toy
And hold there is no sin but ignorance (Prologue 14-15)
Jews, Christians, Muslims—it's all the same when you're Machiavelli; religion is just a tool one uses to manipulate other people. So who agrees with Machiavelli in the play? While Barabas is touted as the main Machiavellian of the play, Ferneze is the one who really trots out religion to do his dirty work for him.
Quote #2
You'll make 'em friends? Are there not Jews enough in Malta,
But thou must dote upon a Christian? (2.3.358-59)
Why can't you just find a nice Jewish boy? (Preferably a doctor.) In addition to demonstrating that parents haven't changed much in 500 years, Barabas is hinting at the dark future: he's already made it clear that Abigail will marry a Christian over his dead body (actually, over Mathias's dead body); just think of how he'll take the news when she becomes a nun.
Quote #3
A fair young maid scarce fourteen years of age,
The sweetest flower in Cytherea's field,
Cropped from the pleasures of the fruitful earth
And strangely metamorphosed nun. (1.3.13-16)
Mathias is eyeing Abigail, who's pretending to be a nun to get back into her old house. Keep those words "strangely metamorphosed" in mind as you read on—unlike Barabas, who straight-up refuses to convert, Abigail's religious commitments are considerably more fluid. (Until they're not.)