Why does Miller have Proctor scream "God is dead"? but later have him say the Lord's Prayer (The Our Father) on the scaffold?

What is the significance of each? How do we reconcile the two? 


The Individual vs. Society in Arthur Miller’s work

Arthur Miller once argued that modern tragedy stems from a protagonist’s struggle against a stifling, strangling environment that has robbed him of his sense of dignity (Steinberg 84-85). The protagonist, Miller said, is any man willing to throw himself into the battle to regain his lost pride and self-respect. And thus is much of Miller’s work patterned; he evokes tragedy by setting the man against the system. What varies is the degree to which the protagonist is a hero, and the degree to which the work is a condemnation of societal flaws.

How and why does John Proctor embody the tragic hero as defined above by Miller?