Unable to live within the framework of the Christian theology, show Faustus was also not satisfied after taking up necromancy and leaving God.
The first indicator that Faustus will not be satisfied after mastering magic and making a compact with the Devil is Mephistophilis' response to him when required to fulfill Faustus' commands, what ever they may be, including releasing the moon's orbit or releasing the ocean's boundaries:
FAUST. To do whatever Faustus shall command,
Be it to make the moon drop from her sphere,
Or the ocean to overwhelm the world.
Mephisto answers a very clear no, saying that he takes his orders from Lucifer and no one else:
MEPHIST. I am a servant to great Lucifer,
And may not follow thee without his leave:
No more than he commands must we perform.
Another indication that Faustus will be dissatisfied is the conversation he and Mephisto have later about specific knowledge Faustus wants. You'll recall from Faustus' introductory speech that he wants to control all the elements of the world and have dominion over all. In view of this, he asks Mephisto who made the world. Mephisto says he won't tell. Soon Lucifer himself comes to remind Faustus that he is damned and that his knowledge will encompass what Lucifer wants him to know; this is a definite departure from Faustus' original plans.
FAUSTUS. ... Tell me who made the world?
MEPHIST. I will not.
FAUSTUS. Sweet Mephistophilis, tell me.
MEPHIST. Move me not, for I will not tell thee.
FAUSTUS. Villain, have I not bound thee to tell me any thing?
This conversation with Mephisto drives Faustus to call upon the name of Christ to "Seek to save distressed Faustus' soul!" which leads in to a final example showing Faustus' dissatisfaction. At the end of the play, the Old Man and the Scholars come to help Faustus turn at the last minute and express repentance and seek salvation from God for compacting with Lucifer. Yet, two things prevent Faustus from doing this: (1) he asks the Old Man how to do this but has no chance to hear the answer; (2) he fears the physical pain Mephistophilis and Lucifer have promised him if he tries to call upon God. His agonies in the last scene clearly show his dissatisfaction:
O, I'll leap up to my God!—Who pulls me down?—
See, see, where Christ's blood streams in the firmament!
One drop would save my soul, half a drop: ah, my Christ!—
Ah, rend not my heart for naming of my Christ!
No, Faustus, curse thyself, curse Lucifer
That hath depriv'd thee of the joys of heaven.