The evil angels are permanently appearing in the Bible, but it is instructive to note that there is no sign of any dualism or conflict between two equal principles, one good angel and the other evil angel. The conflict depicted is rather that waged on earth between the Kingdom of God and the Kingdom of the Evil One, but the latter's inferiority is always supposed.
The existence, then, of this inferior, and therefore created, spirit, has to be explained.
A spirit that serves as the counterpart to the good angel and provides Faustus with reasons not to repent for sins against God. The evil angel represents the evil half of Faustus's conscience.
In the New Testament the speedy advent of this kingdom is the one theme: Do penance: for the kingdom of heaven is at hand, said the Baptist, and Christ's opening words to the people do but repeat that message. At every stage in His teaching the advent of this kingdom, its various aspects, its precise meaning, the way in which it is to be attained, form the staple of His discourses, so much so that His discourse is called the gospel of the kingdom.