Mark 5:11 There on the hillside, a great herd of pigs was feeding. 5:12 And the demonic spirits begged him, “Send us into the pigs. Let us enter them.” 5:13 Jesus gave them permission. So the unclean spirits came out and went into the pigs. Then the herd rushed down the steep slope into the lake, and about two thousand were drowned in the lake.

Why did Jesus allow the demons to enter (and then destroy) the pigs, when he could have destroyed the demons there and then?  Subsidiary questions are sometimes raised around the apparent cruelty to the pigs, and the loss of their owners’ livelihoods.

Some people object to the idea that a herd of animals should be destroyed in this way (to say nothing of the expense to the owners). Spong (Rescuing the Bible from Fundamentalism) says:

‘It did not seem to occur to Mark that the swine represented someone’s livelihood, indeed, probably a person’s entire fortune.’

In reply, it must be remembered that (a) Jesus did not send the demons into the pigs (he merely gave permission); (b) he did not cause the pigs to be destroyed; (c) one person’s life is worth far more than a whole herd of pigs; (d) the miracle no doubt benefited the whole community, which was freed from the peril and terror of an uncontrollable maniac, and probably from further interference from the demons who had been expelled from him.

As Stein, (NAC on Luke) remarks:

‘Various commentators’ concern for the owners’ economic loss may be due to a greater sensitivity for the property of others than the Evangelists had, but it may also reveal a lesser concern for the spiritual issues involved.’

Keener (IVP Bible Background Commentary) notes that only Gentiles and non-observant Jews would keep pigs.  They would have been regarded as suitable hosts for unclean spirits.  Ancient exorcists sometimes found that evil spirits would ask for concessions when they found the pressure to evacuate their host became intolerable.

Whatever else was the significance of the demons leaving the man and entering the pigs, it certainly demonstrated most dramatically and decisively the completeness of the deliverance.

Trench says,

‘If this granting of the evil spirits’ request helped in any way the cure of the man, caused them to relax their hold on him more easily, mitigated the paroxysm of their going forth, this would have been motive enough.  Or, still more probably, it may have been necessary for the permanent healing of the man, that he should have an outward evidence and testimony that the hellish powers which held him in bondage, had quitted their hold.’

But the episode is best understood from an eschatological perspective.  Evans, WBC on Luke, comments:

‘The agreement of Jesus to this arrangement has been a puzzle to many…The account certainly does not suggest that this was the only way Jesus could get the demons out of the man. In the situation he is clearly portrayed as a plenipotentiary. The underlying difficulty is that of any theodicy in the face of the fact of continuing evil (cf. Rev 20:3). Schürmann, 486, points to the continuing activity of the demonic during the gentile mission (Acts 13:6–11; 16:16–18; 19:13–16).  Luke 11:24–26 presumes that an expelled spirit will still have the possibility of continuing to work mischief. The perspective of our pericope is that though Jesus is actively engaged in rescuing those who have become the victims of the Devil’s minions (cf. 11:5–22), for whatever reason the time is not yet for bringing to ultimate judgment and destruction these forces of evil. Only in an anticipatory way do the demons come up against, in Jesus, the one who means their ultimate demise.’

Evans adds:

‘Jesus’ agreement to the request has troubled modern readers of the text, especially in light of the fate of the animals. In the (Jewish) perspective of the story, the pigs are of no value: to put the demons there is to put them safely out of the way, at least for the moment. Jesus’ agreement to having the demons remain on the loose to work their mischief is more difficult. But continuing evil is a fact, despite all that has been achieved by Jesus, and this was evident in the early missionary endeavors of the church as portrayed in Acts. The demons meet in Jesus the one who means their ultimate demise, but for whatever reason the time for their ultimate judgment and destruction has not yet come.’

The demons fear that the time for their final destruction has come.  In order to escape total and final punishment, the demons plead with Jesus to allow them to inhabit the herd of pigs.

Christ, in his mercy, delays the final judgement that would have finally destroyed the demons, cf. Mt 8:29.  And again, in his mercy, he allows them them to destroy an entire herd of pigs rather than destroy a single human being.

The contributor to Hard Sayings of the Bible writes:

‘This is the only exorcism in the Gospels in which the demons answer back to Jesus. In fact, they do so after Jesus commands them to leave the man (a detail not mentioned in Matthew). Their concern is that they not be tormented, that is, sent to hell (Matthew specifically adds “before the time,” meaning before the final judgment). Why would they say this? First, Jewish teaching was that demons were free to torment people until the last judgment (see Jubilees 10:5–9 and 1 Enoch 15–16). Second, Jesus’ appearance and power to expel them looked to them as if he were beginning the final judgment too early. Therefore, the permission to enter the pigs is an admission that the last judgment is not yet taking place. The demons are still free to do their destructive work. Nevertheless, wherever the King is present he brings the kingdom and frees people from the power of evil.’