No, this is not the beginning of a bad joke...It is a reference, of course, to a key incident in this week's Parasha:
And the King of Sedom came out to greet him [Avram], after he [Avram] returned from smiting Kedorlaomer and the kings who were with him; and he met him in the Valley of Shaveh, which was the valley of the king. And Malkizedeq, King of Shalem, brought out bread and wine; and he was a priest to the Most High God. And he blessed him and said, 'Blessed is Avram to the Most High God, possessor of Heaven and Earth. And blessed is the Most High God who delivered your enemies into your hand." And he gave him a tenth of everything.
Certainly the most fascinating and mysterious character in this whole episode is Malkizedeq. Who was he? How did he become a priest of God in a world immersed in idolatry? And, even more basically - why did he make a sudden appearance at the conclusion of the battle against the four kings? We understand that the King of Sedom came to negotiate the release of his citizens who were taken hostage by Kedorlaomer and liberated by Avram. But no explanation is offered for the presence of Malkizedeq at this important meeting.
Before we can account for Malkizedeq's role in this situation, we must identify him. The Midrash and the majority of classical commentators maintain that Malkizedeq was none other than Shem, the son of Noah. If we accept this interpretation, then the fact that he was a worshipper of Hashem is easier to fathom. Unlike Avram, who had to discover the existence of God independently, Shem would have received a tradition of monotheism directly from his father.
However, the traditional interpretation rests upon a foundation that has been shaken by modern scholarship. We now know that El Elyon was not Hashem; rather, it was a Canaanite god popular during the period of the Patriarchs. Most likely, Malkizedeq was a priest of this god, and not a believer in the God of Avram. Therefore, we need not feel compelled to identify Malkizedeq with Shem in order to account for his religious orientation. His theological beliefs were quite typical of the era in which he lived.
(See the commentary of Daat Miqra, where this view is adopted and also attributed to the Ramban; however, it is difficult, in my opinion, to interpret Nachmanides this way.)
We can now explain why Avram chose to refer to God as 'El Elyon' in his response to the King of Sedom:
And Avram said to the King of Sedom, "I lift my hand to Hashem, Most High God, possessor of Heaven and Earth...."
Malkizedeq perceived Avram as one who was favored by El Elyon, the supreme god of the Canaanite pantheon. He tried to understand Avram in terms of his own religious categories. In all likelihood, the King of Sedom concurred with this view.
Through a subtle manipulation of language, Avram corrected this misconception. He declared his allegiance to Hashem, who is the Most High God. The addition of the name 'Hashem' differentiated Avram's concept of divinity from the one expressed by Malkizedeq. Unlike the pagan god El Elyon, the God of Avram is One, eternal, incorporeal and transcendent.
Through adopting the Canaanite terminology, Avram asserted his rejection of idolatry while simultaneously educating Malkizedeq. He explained his belief in a way that a Canaanite priest could comprehend, while emphasizing the name "Hashem" so that the uniqueness of his philosophy was not diluted.
Avram's dialogue with the King of Sedom is also noteworthy. He refused to avail himself of any of the spoils of war:
"I shall not take even a string or shoelace - I shall not take anything of yours - that you shall not say, 'I made Avram wealthy.'"
Here Avram demonstrated that his involvement in military conflict was not for the purpose of building an empire or amassing wealth. It was purely with an eye to rescuing his nephew from harm. Avram walked away from the war victorious but disinterested in capitalizing on his success from a political standpoint. This must have left the King of Sedom with a strong impression of the greatness of Avram and the sophistication of his principles.
We can now better understand the reason why three very different personalities - Avram, the King of Sedom and Malkizedeq - all converged after the battle against the four kings.
The military campaign that Avram waged was a turning point in establishing his reputation in the land. His success attracted the interest of politicians and philosophers, kings and theologians. All now recognized that there was something very special about Avram. All were interested in explaining what it was. This required Avram to expound upon his philosophical views as well as to share his attitude toward wealth and honor. He showed Malkizedeq and the King of Sedom that his understanding of God demanded a change not only in belief but in lifestyle and values. Love of power and luxury cannot be reconciled with worship of the God of Avram.
The story of the meeting of the King of Sedom, Malkizedeq and Avram illustrates a key dimension of Avram's mission. Avram's ultimate purpose was to revolutionize both theology and politics. He wished to draw mankind toward proper knowledge and service of the One God, and away from the pursuit of material gain and self-aggrandizement. Avram's interaction with key religious and political figures afforded him the opportunity to spread his message and to try and effectuate positive change in society. Unfortunately, mankind has yet to internalize the lessons he taught.