How do you know whether the word "seed" in the Old Testament means Christ or the nation of Israel?
The Hebrew word for seed can be either singular or plural, so its meaning must be determined from the context. When the text speaks of many earthly descendants, it refers to the nation of Israel; when it is singular, it points to Christ, the Messiah.
Les explains that the Hebrew word behind “seed” is a quirk: the same identical word can be plural or singular, somewhat like the English word “sheep,” which can describe one sheep or many sheep. Therefore, you have to discern from the context whether the text is speaking singularly of the Messiah, Christ, or plurally of the children of Israel. In Genesis 13, the context shows it is plural: God says, “I will make thy seed, the offspring, as the dust of the earth.” Les points out that dust is earthly, so this speaks of Abraham’s earthly progeny, the nation of Israel, likened to the sand of the sea and compared with the other nations of the ancient world.
And I will make thy seed as the dust of the earth: so that if a man can number the dust of the earth, then shall thy seed also be numbered.