And no marvel, for Satan himself is transformed into an angel of light. (2 Cor 11:14)
In this text, Paul shows that he accepted the contemporary belief in an external, supernatural Satan, contra the arguments of certain Christadelphian apologists. Paul clearly accepts the belief of his time in an external supernatural "Satan" who could disguise himself into various forms. The verb used by Paul is μετασχηματίζω and is used in the intertestamental literature describing how this external, supernatural being masquerades in various forms to deceive:
And while I was inside, Satan, having disguised (μετασχηματίζω) himself as a beggar, knocked on the door. (Testament of Job 6:4 [dated from the first century BC to the first century AD])
And Satan, knowing this, was transformed (μετασχηματίζω) into a bread seller. (Testament of Job 23:1)
As with many other texts (Matt 4:1-11 [cf. Mark 1:12-13; Luke 4:1-13]; Jude 9), the New Testament affirms the “traditional” view of the ontological existence of Satan. I hope this serves as a wake-up call to Christadelphians and others who, as a tenet of their faith, argue that the Bible rejects the ontological existence of supernatural evil, one of the many fatal flaws in their theology since the movement was founded in 1848 by Dr. John Thomas (others would include their rejection of the personal pre-existence and deity of Jesus; sola scriptura; and the state of the dead).