This has to do with their modus operandi.
Satan and Elijah both traverse the world, seeking out people to test or to help, as is their wont. What I find fascinating is that in order to do it, they disguise themselves. These disguises, and the fact that both of them make extensive use of them, interest me very much.
Satan, for example disguises himself as a:
4. Beggar or young man
Elijah disguises himself as a:
1. Court official
6. Ugly man
And both Satan and Elijah wear disguises beyond the ones I have mentioned.
In fact, Satan and Elijah are almost opposites of one another- in their angelic form. It seems quite suitable that this should be so, as Elijah was rebuked for being too accusatory or harsh on his people; it follows that his actions to help the deserving or worthy against another accuser's wishes are fitting.
Where/ when do they disguise themselves?
As a bird:
- And he walked upon the roof of the king's house: and from the roof he saw a woman washing herself; and the woman was very beautiful to look upon.7 Now Bath Sheba was cleansing her hair behind a screen,8 when Satan came to him, appearing in the shape of a bird. He shot an arrow at him, which broke the screen, thus she stood revealed, and he saw her. Immediately, And David sent and enquired after the woman. And one said, Is not this Bath Sheba, the daughter of Eliam, the wife of Uriah the Hittite?
As a stag:
One day, when he [David] ventured forth to Sekhor Bizzae,23 Satan appeared before him in the guise of a deer. He shot arrows at him, but did not reach him, and was thus led on until inveigled into the land of the Philistines. When Ishbi-benob espied him, he exclaimed, 'It is he who slew my brother Goliath.' So he bound him, doubled him up and cast him under an olive press; but a miracle was wrought, and the ground softened under him.
- (Perhaps this is the foundation for the idea of 'The White Hart' or 'The White Stag,' very important in Celtic and Arthurian tradition, often actually a woman wearing the form of a hart- here's a story that should illustrate that. The White Hart cannot be caught or killed and serves as a symbol, something which Kings, such as Arthur, chase fruitlessly, often leading them to adventure.)
As a woman:
- Rabbi Meir used to scoff at sinners for giving in to their desires. One day, Satan appeared to him in the guise of a beautiful woman on the other side of the river. There was no ferry, so Rabbi Meir grasped the rope-bridge and proceeded across. When he reached halfway, Satan left him saying: Had they not declared in Heaven, "Beware of Rabbi Meir and his Torah" your life would not have been worth two maahs [a maah is a small coin]. (Kiddushin 81a).
A similar incident is recounted involving another great sage, Rabbi Akiva:
Rabbi Akiva used to scoff at sinners for giving in to their desires. One day, Satan appeared to him in the guise of a beautiful woman on a tree. Rabbi Akiva grabbed the tree and began climbing it, but when he reached halfway, Satan left him saying: Had they not declared in Heaven, "Beware of Rabbi Akiva and his Torah" your life would not have been worth two maahs. (Kiddushin 81a).
~Quoted from here
As a beggar and young man:
- הלך מעליו ונדמה לבחור ועמד על ימינו של יצחק א"ל לאן אתה הולך, א"ל ללמוד תורה, א"ל בחייך או במיתתך,
Midrash Tanchuma, parashat Vayera
I can't find the part about his being a beggar right now, but I know he appears as a beggar and an old man- an old man to Avraham, and a beggar to Sarah.
All right, so that's the Satan.
What about Eliyahu?
(All the stories about Eliyahu can be found here. Unfortunately, Sacred-Texts is quoting 'Legends of the Jews' by Louis Ginzberg, who has long lists of indexes in a completely different volume, so while I am well-nigh unto positive all the statements are accurate, I don't know the sources. If you could provide me with them, that would be wonderful. I'm only going to quote a few examples here. Oh, and I would be very indebted to anyone who feels like buying me Legends of the Jews.)
As a court official:
- It once happened that the Israelites had to send a present to the imperial house, and Nahum was selected to carry out the mission, because it was quite usual for miracles to be performed on his account. They intrusted to him a casket containing precious stones and pearls. When he arrived at his quarters for the night, thieves became aware of his treasure, and they removed the valuables contained in the casket, substituting therefor dry earth. When he arrived at the imperial palace, the casket was opened, and it being observed that it contained nothing but earth, the emperor became very wroth and determined to destroy all the Jews, thinking that they had merely mocked him. Nahum, however, said to himself: "Even this will lead to good." When a conference was held as to the manner in which the Jews were to be destroyed, Elijah appeared disguised as one of the councillors, and after the conference said: "Perhaps this earth is of the greatest value, as it may be the same earth which Abraham their father had within his domain, and which possessed the merit of turning into swords which would cut down the enemy when thrown at a hostile army. The coarser pieces would turn into arrows when thrown at the enemy, as it is written [Isaiah, xli. 2]: He rendered as earth his sword, as driven stubble his bow.'" 1
~Somewhere in Ta'anis
As a harlot:
When the Roman bailiffs were pursuing Rabbi Meir, Elijah joined him in the guise of a harlot. The Roman emissaries desisted from their pursuit, for they could not believe that Rabbi Meir would choose such a companion.
As an Arab:
- In the form of an Arab, he once appeared before a very poor man, whose piety equalled his poverty. He gave him two shekels. These two coins brought him such good fortune that he attained great wealth. But in his zeal to gather worldly treasures, he had no time for deeds of piety and charity. Elijah again appeared before him and took away the two shekels. In a short time the man was as poor as before. A third time Elijah came to him. He was crying bitterly and complaining of his misfortune, and the prophet said: "I shall make thee rich once more, if thou wilt promise me under oath thou wilt not let wealth ruin they character." He promised, the two shekels were restored to him, he regained his wealth, and he remained in possession of it for all time, because his piety was not curtailed by his riches.
As a horseman:
- He exercised the functions of a physician upon Rabbi Shimi bar Ashi, who had swallowed a noxious reptile. Elijah appeared to him as an awe-inspiring horseman, and forced him to apply the preventives against the disease to be expected in these circumstances.
As a slave:
- poor man, the father of a family, in his distress once prayed to God: "O Lord of the world, Thou knowest, there is none to whom I can tell my tale of woe, none who will have pity upon me. I have neither brother nor kinsman nor friend, and my starving little ones are crying with hunger. Then do Thou have mercy and be compassionate, or let death come and put an end to our suffering." His words found a hearing with God, for, as he finished, Elijah stood before the poor man, and sympathetically inquired why he was weeping. When the prophet had heard the tale of his troubles, he said: "Take me and sell me as a slave; the proceeds will suffice for thy needs." At first the poor man refused to accept the sacrifice, but finally yielded, and Elijah was sold to a prince for eighty denarii. This sum formed the nucleus of the fortune which the poor man amassed and enjoyed until the end of his days. The prince who had purchased Elijah intended to build a palace, and he rejoiced to hear that his new slave was an architect. He promised Elijah liberty if within six months he completed the edifice. After nightfall of the same day, Elijah offered a prayer, and instantaneously the palace stood in its place in complete perfection. Elijah disappeared. The next morning the prince was not a little astonished to see the palace finished. But when he sought his slave to reward him, and sought him in vain, he realized that he had had dealings with an angel. Elijah meantime repaired to the man who had sold him, and related his story to him, that he might know he had not cheated the purchaser out of his price; on the contrary, he had enriched him, since the palace was worth a hundred times more than the money paid for the pretended slave.
And so on and so forth.
It's brilliant, isn't it? You notice that Elijah is (I believe) the first prophet to revive another human being from the dead. We learn about how he is given the 'Keys,' how in order to revive this boy he is given the Key of Death. So from the very beginning, Elijah is interacting with/ opposing the Angel of Death, who is identified with Satan. However, Elijah is also very similar to the Satan; he is an accusatory person and is rebuked for being so.
- Observe that at first the scriptures state, 'And the Lord came unto him and said, 'What doest thou here, Elijah?' And Elijah answered and said, 'I have been very zealous for the Lord God of hosts, because the children of Israel have forsaken thy covenant a,' (1 Kings XIX. 9-10). Then said God unto him, 'I swear by thy life that wherever and whenever my children shall practice and obey my covenant, there shalt thou be present and thy mouth which now testifies that the children of Israel have forsaken my covenant, shall also testify when they keep it.' We are also taught by tradition that Elijah was punished for making himself the accuser of God's children."
Fascinating, isn't it, that Elijah the former-Accuser and Satan the Accuser are now similar creatures? Elijah does not die, but is taken up to heaven alive, where he becomes an angel. Like Satan, he flies about the world (this is proved in various places) and like Satan, he assumes many different guises. Unlike Satan, however, he rewards those who are good rather than testing them. He is the Defense; he now testifies to the Jews keeping the covenant.
Most interesting is Louis Ginzberg's conclusion to this section, "The last act of Elijah's brilliant career will be the execution of God's command to slay Samael, and so banish evil forever."
Satan is often identified with Samael. Isn't this fitting? Elijah and Satan share similar qualities, and so Elijah's killing Satan is very suitable. It's almost as though Elijah is killing his opposite, the other side of himself, or at the very least the darker version. It is honorable for Elijah to kill Satan, noble. Because Satan and Elijah are equals, or so it would appear. If Satan is to perish at anyone's hands, it makes sense that it be Elijah (or, if not Elijah, then God), because that is the only truly noble, truly befitting death for such a fascinating, formidable creation. For anyone less to spell his end would be an insult. But for Elijah...well. Elijah is The Defense, Satan, The Prosecutor. For Elijah to triumph is so, so brilliant- in both the literary and cosmic sense of the word.