Doctor Faustus is the story of a man who sells his soul to the Devil to gain supernatural powers. It is based on the Christian theological concepts of the immortality of the soul, the nature of sin, the reality of Heaven and Hell, and the possibility of spiritual redemption.
Marlowe establishes the ideas and themes of his play in the very first scene. We learn from the Chorus that Faustus is a brilliant young man who has risen from working-class origins to be the foremost theologian at the University of Wittenberg (spelled as "Wertenberg" in the text). Faustus is familiar with all the aforementioned Christian concepts. However, he is not content with the answers theology provides about the nature of the universe and humanity's place within it, believing himself too brilliant to be limited by such constraints. The Chorus compares him to Icarus, who died after flying too close to the sun:
...swoln with cunning, of a self-conceit,
His waxen wings did mount above his reach,
And, melting, heavens conspir'd his overthrow;
For, falling to a devilish exercise,
And glutted now with learning's golden gifts,
He surfeits upon cursed necromancy;
Nothing so sweet as magic is to him,
Which he prefers before his chiefest bliss[.]
Faustus's failure to accept Christian doctrine and his desire to challenge the natural order through use of magic is the root of his downfall. He could be grateful for the life God has given him as a respected theologian at a prominent university; instead, he chooses to pursue forbidden knowledge, even though this carries the risk of damnation. Faustus's "chiefest bliss" should be the understanding that, if he lives a pious life, his soul will go to Heaven. He rejects this abstract understanding in favor of gaining more power in his earthly life.
These metaphysics of magicians,
And necromantic books are heavenly [...]
O, what a world of profit and delight,
Of power, of honour, of omnipotence,
Is promis'd to the studious artizan!
Marlowe has used the Chorus to set the scene before introducing us to Faustus himself. The Chorus describes the arc of Faustus's life, showing his upward trajectory from humble birth to academic achievement, and then briefly indicates how Faustus stands to lose it all. When Faustus enters the study, he confirms the Chorus's description of him by showing his mastery of various subjects (medicine, law, and theology). He then confirms the Chorus's judgment of him by showing that his new infatuation is magic. Magic promises the practitioner immediate gratification, while theology demands lifelong adherence to strict moral guidelines in the hope of everlasting life after death.
The choice between temporary satisfaction and everlasting life should be an obvious one, and would have been to Marlowe's audience. But Faustus is unsure: what if there is no everlasting life? Should people forego earthly pleasures on the off-chance that eternal bliss awaits them after death? He thinks not, but the Chorus implies that he is making the wrong choice. Faustus's behavior and the consequences of his behavior are thus predicted in the opening scene.