What is the dramatic significance of good angel and evil angel in Marlowe’s Doctor Faustus?

The Good Angel and the Evil Angel in Marlowe's Dr Faustus are physical manifestations of the good and evil impulses that battle for supremacy in Faustus's conscience. Bringing the two competing sides of Faustus's conscience alive in the form of the two angels makes the dramatic tension between them more palpable and more dramatically explicit. It is easier for an audience to empathize with and invest in a battle between two anthropomorphized angels than it is for an audience to empathize with and invest in a battle between two abstract concepts.
The angels are also dramatically significant in that they create suspense for the audience. We wonder which angel will prove the stronger influence upon Faustus, and we wonder which will be proven correct as regards Faustus' fate. The Good Angel tells him repeatedly that it is never too late to repent, whereas the Evil Angel promises that devils will tear him to pieces if he ever does repent. The Good Angel warns Faustus that his transgressive pride will bring "God's heavy wrath upon (his) head," whereas the Evil Angel encourages Faustus to enjoy his powers and "Be . . . on earth as Jove is in the sky." Faustus is constantly pulled back and forth between the two angels, and from this battle, much of the play's dramatic tension derives—and also much of its suspense.