How we cite our quotes: (Act.Scene.Line)
Quote #4
FAUSTUS
Seeing Faustus hath incurred eternal death
By desperate thoughts against Jove's deity,
Say, he surrenders up to him his soul. (1.3.86-88)
Faustus's logic in surrendering his soul to the devil is similar to his thinking when he turned to magic: "I am already damned, so why not go whole hog?" In other words, Faustus has already blasphemed against God, and has therefore lost all hope of heaven. There's no turning back now.
Quote #5
FAUSTUS
Now, Faustus, must thou needs be damned?
Canst thou not be saved?
What boots it, then, to think on God or heaven?
Away with such vain fancies, and despair.
Despair in God and trust in Beelzebub. (2.1.1-5)
Or maybe Faustus isn't quite convinced that he has zero hope of heaven. In this quote, he's still considering the possibility of salvation for himself. He seems almost desperate here, like he's clinging to one last hope, no matter how pathetic. But of course, he'll soon be distracted by the devils, so no matter.
Quote #6
FAUSTUS
"Faustus gives to thee his soul." O, there it stayed!
Why shouldst thou not? Is not thy soul thine own? (2.1.65-66)
The question of whether or not man's soul belongs to him is actually a question about Predestination in disguise. Does a man have free will to choose whom he'll serve, or does his soul already belong to God or the Devil from the moment he is born?