What does Genesis 14:19 mean?

The blessing of verses 19 and 20 comes in a unique context. Two kings have come to meet Abram, who is returning from his victory over the four kings from the east. This victory rescued his nephew, Lot, along with and all of the people and possessions of both Lot and Sodom in tow.

One of the visiting kings is Bera, the king of Sodom (Genesis 14:2). The other king is the enigmatic Melchizedek, the king of Salem and a priest of the "Most High God." Scholars present several possible identities for Melchizedek. One of these is that he was king of the city which would later become Jerusalem, based on the name Salem. Another interpretation is that Melchizedek is a temporary, pre-Christ incarnation of God, known as a theophany or a Christophany.

After serving Abram bread and wine, Melchizedek offers a blessing. In blessing Abram, Melchizedek appeals to the God who made and owns all the earth and all the heavens. Abram will acknowledge God's possession of all things by giving, in the following verse, a tenth of the rescued plunder to God's priest Melchizedek. In doing so, Abram not only shows his growing humility, but also recognition that God does not speak to Abram, alone.